diff --git a/MANIFEST b/MANIFEST
index e7135fe6d82e..a53055a1a114 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -1802,9 +1802,6 @@ cpan/Pod-Escapes/lib/Pod/Escapes.pm	Pod::Escapes
 cpan/Pod-Escapes/t/01_about_verbose.t	test Pod::Escapes
 cpan/Pod-Escapes/t/10_main.t		test Pod::Escapes
 cpan/Pod-Escapes/t/15_name2charnum.t	test Pod::Escapes
-cpan/Pod-Perldoc/corpus/no-head.pod		test file for Pod-Perldoc
-cpan/Pod-Perldoc/corpus/perlfunc.pod		test file for Pod-Perldoc
-cpan/Pod-Perldoc/corpus/utf8.pod		test file for Pod-Perldoc
 cpan/Pod-Perldoc/lib/Pod/Perldoc.pm		guts of the 'perldoc' utility
 cpan/Pod-Perldoc/lib/Pod/Perldoc/BaseTo.pm	utility module for perldoc
 cpan/Pod-Perldoc/lib/Pod/Perldoc/GetOptsOO.pm	options parsing for perldoc
diff --git a/Porting/Maintainers.pl b/Porting/Maintainers.pl
index 825aa502bf6a..efb8119273fe 100755
--- a/Porting/Maintainers.pl
+++ b/Porting/Maintainers.pl
@@ -956,6 +956,9 @@ package Maintainers;
             # utils first
             'perldoc',
 
+            # files only used for manual testing
+            qr[^corpus/],
+
             # https://rt.cpan.org/Ticket/Display.html?id=116827
             't/02_module_pod_output.t'
         ],
diff --git a/cpan/Pod-Perldoc/corpus/no-head.pod b/cpan/Pod-Perldoc/corpus/no-head.pod
deleted file mode 100644
index aa6381958a99..000000000000
--- a/cpan/Pod-Perldoc/corpus/no-head.pod
+++ /dev/null
@@ -1,5 +0,0 @@
-=pod
-
-This is a line of text
-
-=cut
diff --git a/cpan/Pod-Perldoc/corpus/perlfunc.pod b/cpan/Pod-Perldoc/corpus/perlfunc.pod
deleted file mode 100644
index 604123daf8b5..000000000000
--- a/cpan/Pod-Perldoc/corpus/perlfunc.pod
+++ /dev/null
@@ -1,8298 +0,0 @@
-=head1 NAME
-X<function>
-
-perlfunc - Perl builtin functions
-
-=head1 DESCRIPTION
-
-The functions in this section can serve as terms in an expression.
-They fall into two major categories: list operators and named unary
-operators.  These differ in their precedence relationship with a
-following comma.  (See the precedence table in L<perlop>.)  List
-operators take more than one argument, while unary operators can never
-take more than one argument.  Thus, a comma terminates the argument of
-a unary operator, but merely separates the arguments of a list
-operator.  A unary operator generally provides scalar context to its
-argument, while a list operator may provide either scalar or list
-contexts for its arguments.  If it does both, scalar arguments 
-come first and list argument follow, and there can only ever
-be one such list argument.  For instance, splice() has three scalar
-arguments followed by a list, whereas gethostbyname() has four scalar
-arguments.
-
-In the syntax descriptions that follow, list operators that expect a
-list (and provide list context for elements of the list) are shown
-with LIST as an argument.  Such a list may consist of any combination
-of scalar arguments or list values; the list values will be included
-in the list as if each individual element were interpolated at that
-point in the list, forming a longer single-dimensional list value.
-Commas should separate literal elements of the LIST.
-
-Any function in the list below may be used either with or without
-parentheses around its arguments.  (The syntax descriptions omit the
-parentheses.)  If you use parentheses, the simple but occasionally 
-surprising rule is this: It I<looks> like a function, therefore it I<is> a
-function, and precedence doesn't matter.  Otherwise it's a list
-operator or unary operator, and precedence does matter.  Whitespace
-between the function and left parenthesis doesn't count, so sometimes
-you need to be careful:
-
-    print 1+2+4;      # Prints 7.
-    print(1+2) + 4;   # Prints 3.
-    print (1+2)+4;    # Also prints 3!
-    print +(1+2)+4;   # Prints 7.
-    print ((1+2)+4);  # Prints 7.
-
-If you run Perl with the B<-w> switch it can warn you about this.  For
-example, the third line above produces:
-
-    print (...) interpreted as function at - line 1.
-    Useless use of integer addition in void context at - line 1.
-
-A few functions take no arguments at all, and therefore work as neither
-unary nor list operators.  These include such functions as C<time>
-and C<endpwent>.  For example, C<time+86_400> always means
-C<time() + 86_400>.
-
-For functions that can be used in either a scalar or list context,
-nonabortive failure is generally indicated in scalar context by
-returning the undefined value, and in list context by returning the
-empty list.
-
-Remember the following important rule: There is B<no rule> that relates
-the behavior of an expression in list context to its behavior in scalar
-context, or vice versa.  It might do two totally different things.
-Each operator and function decides which sort of value would be most
-appropriate to return in scalar context.  Some operators return the
-length of the list that would have been returned in list context.  Some
-operators return the first value in the list.  Some operators return the
-last value in the list.  Some operators return a count of successful
-operations.  In general, they do what you want, unless you want
-consistency.
-X<context>
-
-A named array in scalar context is quite different from what would at
-first glance appear to be a list in scalar context.  You can't get a list
-like C<(1,2,3)> into being in scalar context, because the compiler knows
-the context at compile time.  It would generate the scalar comma operator
-there, not the list construction version of the comma.  That means it
-was never a list to start with.
-
-In general, functions in Perl that serve as wrappers for system calls ("syscalls")
-of the same name (like chown(2), fork(2), closedir(2), etc.) return
-true when they succeed and C<undef> otherwise, as is usually mentioned
-in the descriptions below.  This is different from the C interfaces,
-which return C<-1> on failure.  Exceptions to this rule include C<wait>,
-C<waitpid>, and C<syscall>.  System calls also set the special C<$!>
-variable on failure.  Other functions do not, except accidentally.
-
-Extension modules can also hook into the Perl parser to define new
-kinds of keyword-headed expression.  These may look like functions, but
-may also look completely different.  The syntax following the keyword
-is defined entirely by the extension.  If you are an implementor, see
-L<perlapi/PL_keyword_plugin> for the mechanism.  If you are using such
-a module, see the module's documentation for details of the syntax that
-it defines.
-
-=head2 Perl Functions by Category
-X<function>
-
-Here are Perl's functions (including things that look like
-functions, like some keywords and named operators)
-arranged by category.  Some functions appear in more
-than one place.
-
-=over 4
-
-=item Functions for SCALARs or strings
-X<scalar> X<string> X<character>
-
-C<chomp>, C<chop>, C<chr>, C<crypt>, C<hex>, C<index>, C<lc>, C<lcfirst>,
-C<length>, C<oct>, C<ord>, C<pack>, C<q//>, C<qq//>, C<reverse>,
-C<rindex>, C<sprintf>, C<substr>, C<tr///>, C<uc>, C<ucfirst>, C<y///>
-
-=item Regular expressions and pattern matching
-X<regular expression> X<regex> X<regexp>
-
-C<m//>, C<pos>, C<quotemeta>, C<s///>, C<split>, C<study>, C<qr//>
-
-=item Numeric functions
-X<numeric> X<number> X<trigonometric> X<trigonometry>
-
-C<abs>, C<atan2>, C<cos>, C<exp>, C<hex>, C<int>, C<log>, C<oct>, C<rand>,
-C<sin>, C<sqrt>, C<srand>
-
-=item Functions for real @ARRAYs
-X<array>
-
-C<each>, C<keys>, C<pop>, C<push>, C<shift>, C<splice>, C<unshift>, C<values>
-
-=item Functions for list data
-X<list>
-
-C<grep>, C<join>, C<map>, C<qw//>, C<reverse>, C<sort>, C<unpack>
-
-=item Functions for real %HASHes
-X<hash>
-
-C<delete>, C<each>, C<exists>, C<keys>, C<values>
-
-=item Input and output functions
-X<I/O> X<input> X<output> X<dbm>
-
-C<binmode>, C<close>, C<closedir>, C<dbmclose>, C<dbmopen>, C<die>, C<eof>,
-C<fileno>, C<flock>, C<format>, C<getc>, C<print>, C<printf>, C<read>,
-C<readdir>, C<rewinddir>, C<say>, C<seek>, C<seekdir>, C<select>, C<syscall>,
-C<sysread>, C<sysseek>, C<syswrite>, C<tell>, C<telldir>, C<truncate>,
-C<warn>, C<write>
-
-=item Functions for fixed-length data or records
-
-C<pack>, C<read>, C<syscall>, C<sysread>, C<syswrite>, C<unpack>, C<vec>
-
-=item Functions for filehandles, files, or directories
-X<file> X<filehandle> X<directory> X<pipe> X<link> X<symlink>
-
-C<-I<X>>, C<chdir>, C<chmod>, C<chown>, C<chroot>, C<fcntl>, C<glob>,
-C<ioctl>, C<link>, C<lstat>, C<mkdir>, C<open>, C<opendir>,
-C<readlink>, C<rename>, C<rmdir>, C<stat>, C<symlink>, C<sysopen>,
-C<umask>, C<unlink>, C<utime>
-
-=item Keywords related to the control flow of your Perl program
-X<control flow>
-
-C<caller>, C<continue>, C<die>, C<do>,
-C<dump>, C<eval>, C<evalbytes> C<exit>,
-C<__FILE__>, C<goto>, C<last>, C<__LINE__>, C<next>, C<__PACKAGE__>,
-C<redo>, C<return>, C<sub>, C<__SUB__>, C<wantarray>
-
-C<__SUB__> is only available with a C<use v5.16> (or higher) declaration or
-with the C<"current_sub"> feature (see L<feature>).
-
-=item Keywords related to the switch feature
-
-C<break>, C<continue>, C<default>, C<given>, C<when>
-
-Except for C<continue>, these are available only if you enable the
-C<"switch"> feature or use the C<CORE::> prefix.
-See L<feature> and L<perlsyn/"Switch statements">.  
-Alternately, include a C<use v5.10> or later to the current scope.  In Perl
-5.14 and earlier, C<continue> required the C<"switch"> feature, like the
-other keywords.
-
-=item Keywords related to scoping
-
-C<caller>, C<import>, C<local>, C<my>, C<our>, C<package>, C<state>, C<use>
-
-C<state> is available only if the C<"state"> feature
-is enabled or if it is prefixed with C<CORE::>. See
-L<feature>.  Alternately, include a C<use v5.10> or later to the current scope.
-
-=item Miscellaneous functions
-
-C<defined>, C<dump>, C<eval>, C<evalbytes>,
-C<formline>, C<local>, C<my>, C<our>,
-C<reset>, C<scalar>, C<state>, C<undef>, C<wantarray>
-
-=item Functions for processes and process groups
-X<process> X<pid> X<process id>
-
-C<alarm>, C<exec>, C<fork>, C<getpgrp>, C<getppid>, C<getpriority>, C<kill>,
-C<pipe>, C<qx//>, C<readpipe>, C<setpgrp>,
-C<setpriority>, C<sleep>, C<system>,
-C<times>, C<wait>, C<waitpid>
-
-=item Keywords related to Perl modules
-X<module>
-
-C<do>, C<import>, C<no>, C<package>, C<require>, C<use>
-
-=item Keywords related to classes and object-orientation
-X<object> X<class> X<package>
-
-C<bless>, C<dbmclose>, C<dbmopen>, C<package>, C<ref>, C<tie>, C<tied>,
-C<untie>, C<use>
-
-=item Low-level socket functions
-X<socket> X<sock>
-
-C<accept>, C<bind>, C<connect>, C<getpeername>, C<getsockname>,
-C<getsockopt>, C<listen>, C<recv>, C<send>, C<setsockopt>, C<shutdown>,
-C<socket>, C<socketpair>
-
-=item System V interprocess communication functions
-X<IPC> X<System V> X<semaphore> X<shared memory> X<memory> X<message>
-
-C<msgctl>, C<msgget>, C<msgrcv>, C<msgsnd>, C<semctl>, C<semget>, C<semop>,
-C<shmctl>, C<shmget>, C<shmread>, C<shmwrite>
-
-=item Fetching user and group info
-X<user> X<group> X<password> X<uid> X<gid>  X<passwd> X</etc/passwd>
-
-C<endgrent>, C<endhostent>, C<endnetent>, C<endpwent>, C<getgrent>,
-C<getgrgid>, C<getgrnam>, C<getlogin>, C<getpwent>, C<getpwnam>,
-C<getpwuid>, C<setgrent>, C<setpwent>
-
-=item Fetching network info
-X<network> X<protocol> X<host> X<hostname> X<IP> X<address> X<service>
-
-C<endprotoent>, C<endservent>, C<gethostbyaddr>, C<gethostbyname>,
-C<gethostent>, C<getnetbyaddr>, C<getnetbyname>, C<getnetent>,
-C<getprotobyname>, C<getprotobynumber>, C<getprotoent>,
-C<getservbyname>, C<getservbyport>, C<getservent>, C<sethostent>,
-C<setnetent>, C<setprotoent>, C<setservent>
-
-=item Time-related functions
-X<time> X<date>
-
-C<gmtime>, C<localtime>, C<time>, C<times>
-
-=item Functions new in perl5
-X<perl5>
-
-C<abs>, C<bless>, C<break>, C<chomp>, C<chr>, C<continue>, C<default>, 
-C<exists>, C<formline>, C<given>, C<glob>, C<import>, C<lc>, C<lcfirst>,
-C<lock>, C<map>, C<my>, C<no>, C<our>, C<prototype>, C<qr//>, C<qw//>, C<qx//>,
-C<readline>, C<readpipe>, C<ref>, C<sub>*, C<sysopen>, C<tie>, C<tied>, C<uc>,
-C<ucfirst>, C<untie>, C<use>, C<when>
-
-* C<sub> was a keyword in Perl 4, but in Perl 5 it is an
-operator, which can be used in expressions.
-
-=item Functions obsoleted in perl5
-
-C<dbmclose>, C<dbmopen>
-
-=back
-
-=head2 Portability
-X<portability> X<Unix> X<portable>
-
-Perl was born in Unix and can therefore access all common Unix
-system calls.  In non-Unix environments, the functionality of some
-Unix system calls may not be available or details of the available
-functionality may differ slightly.  The Perl functions affected
-by this are:
-
-C<-X>, C<binmode>, C<chmod>, C<chown>, C<chroot>, C<crypt>,
-C<dbmclose>, C<dbmopen>, C<dump>, C<endgrent>, C<endhostent>,
-C<endnetent>, C<endprotoent>, C<endpwent>, C<endservent>, C<exec>,
-C<fcntl>, C<flock>, C<fork>, C<getgrent>, C<getgrgid>, C<gethostbyname>,
-C<gethostent>, C<getlogin>, C<getnetbyaddr>, C<getnetbyname>, C<getnetent>,
-C<getppid>, C<getpgrp>, C<getpriority>, C<getprotobynumber>,
-C<getprotoent>, C<getpwent>, C<getpwnam>, C<getpwuid>,
-C<getservbyport>, C<getservent>, C<getsockopt>, C<glob>, C<ioctl>,
-C<kill>, C<link>, C<lstat>, C<msgctl>, C<msgget>, C<msgrcv>,
-C<msgsnd>, C<open>, C<pipe>, C<readlink>, C<rename>, C<select>, C<semctl>,
-C<semget>, C<semop>, C<setgrent>, C<sethostent>, C<setnetent>,
-C<setpgrp>, C<setpriority>, C<setprotoent>, C<setpwent>,
-C<setservent>, C<setsockopt>, C<shmctl>, C<shmget>, C<shmread>,
-C<shmwrite>, C<socket>, C<socketpair>,
-C<stat>, C<symlink>, C<syscall>, C<sysopen>, C<system>,
-C<times>, C<truncate>, C<umask>, C<unlink>,
-C<utime>, C<wait>, C<waitpid>
-
-For more information about the portability of these functions, see
-L<perlport> and other available platform-specific documentation.
-
-=head2 Alphabetical Listing of Perl Functions
-
-=over 
-
-=item -X FILEHANDLE
-X<-r>X<-w>X<-x>X<-o>X<-R>X<-W>X<-X>X<-O>X<-e>X<-z>X<-s>X<-f>X<-d>X<-l>X<-p>
-X<-S>X<-b>X<-c>X<-t>X<-u>X<-g>X<-k>X<-T>X<-B>X<-M>X<-A>X<-C>
-
-=item -X EXPR
-
-=item -X DIRHANDLE
-
-=item -X
-
-A file test, where X is one of the letters listed below.  This unary
-operator takes one argument, either a filename, a filehandle, or a dirhandle, 
-and tests the associated file to see if something is true about it.  If the
-argument is omitted, tests C<$_>, except for C<-t>, which tests STDIN.
-Unless otherwise documented, it returns C<1> for true and C<''> for false, or
-the undefined value if the file doesn't exist.  Despite the funny
-names, precedence is the same as any other named unary operator.  The
-operator may be any of:
-
-    -r  File is readable by effective uid/gid.
-    -w  File is writable by effective uid/gid.
-    -x  File is executable by effective uid/gid.
-    -o  File is owned by effective uid.
-
-    -R  File is readable by real uid/gid.
-    -W  File is writable by real uid/gid.
-    -X  File is executable by real uid/gid.
-    -O  File is owned by real uid.
-
-    -e  File exists.
-    -z  File has zero size (is empty).
-    -s  File has nonzero size (returns size in bytes).
-
-    -f  File is a plain file.
-    -d  File is a directory.
-    -l  File is a symbolic link.
-    -p  File is a named pipe (FIFO), or Filehandle is a pipe.
-    -S  File is a socket.
-    -b  File is a block special file.
-    -c  File is a character special file.
-    -t  Filehandle is opened to a tty.
-
-    -u  File has setuid bit set.
-    -g  File has setgid bit set.
-    -k  File has sticky bit set.
-
-    -T  File is an ASCII text file (heuristic guess).
-    -B  File is a "binary" file (opposite of -T).
-
-    -M  Script start time minus file modification time, in days.
-    -A  Same for access time.
-    -C  Same for inode change time (Unix, may differ for other platforms)
-
-Example:
-
-    while (<>) {
-        chomp;
-        next unless -f $_;  # ignore specials
-        #...
-    }
-
-Note that C<-s/a/b/> does not do a negated substitution.  Saying
-C<-exp($foo)> still works as expected, however: only single letters
-following a minus are interpreted as file tests.
-
-These operators are exempt from the "looks like a function rule" described
-above.  That is, an opening parenthesis after the operator does not affect
-how much of the following code constitutes the argument.  Put the opening
-parentheses before the operator to separate it from code that follows (this
-applies only to operators with higher precedence than unary operators, of
-course):
-
-    -s($file) + 1024   # probably wrong; same as -s($file + 1024)
-    (-s $file) + 1024  # correct
-
-The interpretation of the file permission operators C<-r>, C<-R>,
-C<-w>, C<-W>, C<-x>, and C<-X> is by default based solely on the mode
-of the file and the uids and gids of the user.  There may be other
-reasons you can't actually read, write, or execute the file: for
-example network filesystem access controls, ACLs (access control lists),
-read-only filesystems, and unrecognized executable formats.  Note
-that the use of these six specific operators to verify if some operation
-is possible is usually a mistake, because it may be open to race
-conditions.
-
-Also note that, for the superuser on the local filesystems, the C<-r>,
-C<-R>, C<-w>, and C<-W> tests always return 1, and C<-x> and C<-X> return 1
-if any execute bit is set in the mode.  Scripts run by the superuser
-may thus need to do a stat() to determine the actual mode of the file,
-or temporarily set their effective uid to something else.
-
-If you are using ACLs, there is a pragma called C<filetest> that may
-produce more accurate results than the bare stat() mode bits.
-When under C<use filetest 'access'> the above-mentioned filetests
-test whether the permission can(not) be granted using the
-access(2) family of system calls.  Also note that the C<-x> and C<-X> may
-under this pragma return true even if there are no execute permission
-bits set (nor any extra execute permission ACLs).  This strangeness is
-due to the underlying system calls' definitions. Note also that, due to
-the implementation of C<use filetest 'access'>, the C<_> special
-filehandle won't cache the results of the file tests when this pragma is
-in effect.  Read the documentation for the C<filetest> pragma for more
-information.
-
-The C<-T> and C<-B> switches work as follows.  The first block or so of the
-file is examined for odd characters such as strange control codes or
-characters with the high bit set.  If too many strange characters (>30%)
-are found, it's a C<-B> file; otherwise it's a C<-T> file.  Also, any file
-containing a zero byte in the first block is considered a binary file.  If C<-T>
-or C<-B> is used on a filehandle, the current IO buffer is examined
-rather than the first block.  Both C<-T> and C<-B> return true on an empty
-file, or a file at EOF when testing a filehandle.  Because you have to
-read a file to do the C<-T> test, on most occasions you want to use a C<-f>
-against the file first, as in C<next unless -f $file && -T $file>.
-
-If any of the file tests (or either the C<stat> or C<lstat> operator) is given
-the special filehandle consisting of a solitary underline, then the stat
-structure of the previous file test (or stat operator) is used, saving
-a system call.  (This doesn't work with C<-t>, and you need to remember
-that lstat() and C<-l> leave values in the stat structure for the
-symbolic link, not the real file.)  (Also, if the stat buffer was filled by
-an C<lstat> call, C<-T> and C<-B> will reset it with the results of C<stat _>).
-Example:
-
-    print "Can do.\n" if -r $a || -w _ || -x _;
-
-    stat($filename);
-    print "Readable\n" if -r _;
-    print "Writable\n" if -w _;
-    print "Executable\n" if -x _;
-    print "Setuid\n" if -u _;
-    print "Setgid\n" if -g _;
-    print "Sticky\n" if -k _;
-    print "Text\n" if -T _;
-    print "Binary\n" if -B _;
-
-As of Perl 5.9.1, as a form of purely syntactic sugar, you can stack file
-test operators, in a way that C<-f -w -x $file> is equivalent to
-C<-x $file && -w _ && -f _>. (This is only fancy fancy: if you use
-the return value of C<-f $file> as an argument to another filetest
-operator, no special magic will happen.)
-
-Portability issues: L<perlport/-X>.
-
-=item abs VALUE
-X<abs> X<absolute>
-
-=item abs
-
-Returns the absolute value of its argument.
-If VALUE is omitted, uses C<$_>.
-
-=item accept NEWSOCKET,GENERICSOCKET
-X<accept>
-
-Accepts an incoming socket connect, just as accept(2) 
-does.  Returns the packed address if it succeeded, false otherwise.
-See the example in L<perlipc/"Sockets: Client/Server Communication">.
-
-On systems that support a close-on-exec flag on files, the flag will
-be set for the newly opened file descriptor, as determined by the
-value of $^F.  See L<perlvar/$^F>.
-
-=item alarm SECONDS
-X<alarm>
-X<SIGALRM>
-X<timer>
-
-=item alarm
-
-Arranges to have a SIGALRM delivered to this process after the
-specified number of wallclock seconds has elapsed.  If SECONDS is not
-specified, the value stored in C<$_> is used. (On some machines,
-unfortunately, the elapsed time may be up to one second less or more
-than you specified because of how seconds are counted, and process
-scheduling may delay the delivery of the signal even further.)
-
-Only one timer may be counting at once.  Each call disables the
-previous timer, and an argument of C<0> may be supplied to cancel the
-previous timer without starting a new one.  The returned value is the
-amount of time remaining on the previous timer.
-
-For delays of finer granularity than one second, the Time::HiRes module
-(from CPAN, and starting from Perl 5.8 part of the standard
-distribution) provides ualarm().  You may also use Perl's four-argument
-version of select() leaving the first three arguments undefined, or you
-might be able to use the C<syscall> interface to access setitimer(2) if
-your system supports it. See L<perlfaq8> for details.
-
-It is usually a mistake to intermix C<alarm> and C<sleep> calls, because
-C<sleep> may be internally implemented on your system with C<alarm>.
-
-If you want to use C<alarm> to time out a system call you need to use an
-C<eval>/C<die> pair.  You can't rely on the alarm causing the system call to
-fail with C<$!> set to C<EINTR> because Perl sets up signal handlers to
-restart system calls on some systems.  Using C<eval>/C<die> always works,
-modulo the caveats given in L<perlipc/"Signals">.
-
-    eval {
-        local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
-        alarm $timeout;
-        $nread = sysread SOCKET, $buffer, $size;
-        alarm 0;
-    };
-    if ($@) {
-        die unless $@ eq "alarm\n";   # propagate unexpected errors
-        # timed out
-    }
-    else {
-        # didn't
-    }
-
-For more information see L<perlipc>.
-
-Portability issues: L<perlport/alarm>.
-
-=item atan2 Y,X
-X<atan2> X<arctangent> X<tan> X<tangent>
-
-Returns the arctangent of Y/X in the range -PI to PI.
-
-For the tangent operation, you may use the C<Math::Trig::tan>
-function, or use the familiar relation:
-
-    sub tan { sin($_[0]) / cos($_[0])  }
-
-The return value for C<atan2(0,0)> is implementation-defined; consult
-your atan2(3) manpage for more information.
-
-Portability issues: L<perlport/atan2>.
-
-=item bind SOCKET,NAME
-X<bind>
-
-Binds a network address to a socket, just as bind(2)
-does.  Returns true if it succeeded, false otherwise.  NAME should be a
-packed address of the appropriate type for the socket.  See the examples in
-L<perlipc/"Sockets: Client/Server Communication">.
-
-=item binmode FILEHANDLE, LAYER
-X<binmode> X<binary> X<text> X<DOS> X<Windows>
-
-=item binmode FILEHANDLE
-
-Arranges for FILEHANDLE to be read or written in "binary" or "text"
-mode on systems where the run-time libraries distinguish between
-binary and text files.  If FILEHANDLE is an expression, the value is
-taken as the name of the filehandle.  Returns true on success,
-otherwise it returns C<undef> and sets C<$!> (errno).
-
-On some systems (in general, DOS- and Windows-based systems) binmode()
-is necessary when you're not working with a text file.  For the sake
-of portability it is a good idea always to use it when appropriate,
-and never to use it when it isn't appropriate.  Also, people can
-set their I/O to be by default UTF8-encoded Unicode, not bytes.
-
-In other words: regardless of platform, use binmode() on binary data,
-like images, for example.
-
-If LAYER is present it is a single string, but may contain multiple
-directives. The directives alter the behaviour of the filehandle.
-When LAYER is present, using binmode on a text file makes sense.
-
-If LAYER is omitted or specified as C<:raw> the filehandle is made
-suitable for passing binary data. This includes turning off possible CRLF
-translation and marking it as bytes (as opposed to Unicode characters).
-Note that, despite what may be implied in I<"Programming Perl"> (the
-Camel, 3rd edition) or elsewhere, C<:raw> is I<not> simply the inverse of C<:crlf>.
-Other layers that would affect the binary nature of the stream are
-I<also> disabled. See L<PerlIO>, L<perlrun>, and the discussion about the
-PERLIO environment variable.
-
-The C<:bytes>, C<:crlf>, C<:utf8>, and any other directives of the
-form C<:...>, are called I/O I<layers>.  The C<open> pragma can be used to
-establish default I/O layers.  See L<open>.
-
-I<The LAYER parameter of the binmode() function is described as "DISCIPLINE"
-in "Programming Perl, 3rd Edition".  However, since the publishing of this
-book, by many known as "Camel III", the consensus of the naming of this
-functionality has moved from "discipline" to "layer".  All documentation
-of this version of Perl therefore refers to "layers" rather than to
-"disciplines".  Now back to the regularly scheduled documentation...>
-
-To mark FILEHANDLE as UTF-8, use C<:utf8> or C<:encoding(UTF-8)>.
-C<:utf8> just marks the data as UTF-8 without further checking,
-while C<:encoding(UTF-8)> checks the data for actually being valid
-UTF-8. More details can be found in L<PerlIO::encoding>.
-
-In general, binmode() should be called after open() but before any I/O
-is done on the filehandle.  Calling binmode() normally flushes any
-pending buffered output data (and perhaps pending input data) on the
-handle.  An exception to this is the C<:encoding> layer that
-changes the default character encoding of the handle; see L</open>.
-The C<:encoding> layer sometimes needs to be called in
-mid-stream, and it doesn't flush the stream.  The C<:encoding>
-also implicitly pushes on top of itself the C<:utf8> layer because
-internally Perl operates on UTF8-encoded Unicode characters.
-
-The operating system, device drivers, C libraries, and Perl run-time
-system all conspire to let the programmer treat a single
-character (C<\n>) as the line terminator, irrespective of external
-representation.  On many operating systems, the native text file
-representation matches the internal representation, but on some
-platforms the external representation of C<\n> is made up of more than
-one character.
-
-All variants of Unix, Mac OS (old and new), and Stream_LF files on VMS use
-a single character to end each line in the external representation of text
-(even though that single character is CARRIAGE RETURN on old, pre-Darwin
-flavors of Mac OS, and is LINE FEED on Unix and most VMS files). In other
-systems like OS/2, DOS, and the various flavors of MS-Windows, your program
-sees a C<\n> as a simple C<\cJ>, but what's stored in text files are the
-two characters C<\cM\cJ>.  That means that if you don't use binmode() on
-these systems, C<\cM\cJ> sequences on disk will be converted to C<\n> on
-input, and any C<\n> in your program will be converted back to C<\cM\cJ> on
-output.  This is what you want for text files, but it can be disastrous for
-binary files.
-
-Another consequence of using binmode() (on some systems) is that
-special end-of-file markers will be seen as part of the data stream.
-For systems from the Microsoft family this means that, if your binary
-data contain C<\cZ>, the I/O subsystem will regard it as the end of
-the file, unless you use binmode().
-
-binmode() is important not only for readline() and print() operations,
-but also when using read(), seek(), sysread(), syswrite() and tell()
-(see L<perlport> for more details).  See the C<$/> and C<$\> variables
-in L<perlvar> for how to manually set your input and output
-line-termination sequences.
-
-Portability issues: L<perlport/binmode>.
-
-=item bless REF,CLASSNAME
-X<bless>
-
-=item bless REF
-
-This function tells the thingy referenced by REF that it is now an object
-in the CLASSNAME package.  If CLASSNAME is omitted, the current package
-is used.  Because a C<bless> is often the last thing in a constructor,
-it returns the reference for convenience.  Always use the two-argument
-version if a derived class might inherit the function doing the blessing.
-SeeL<perlobj> for more about the blessing (and blessings) of objects.
-
-Consider always blessing objects in CLASSNAMEs that are mixed case.
-Namespaces with all lowercase names are considered reserved for
-Perl pragmata.  Builtin types have all uppercase names. To prevent
-confusion, you may wish to avoid such package names as well.  Make sure
-that CLASSNAME is a true value.
-
-See L<perlmod/"Perl Modules">.
-
-=item break
-
-Break out of a C<given()> block.
-
-This keyword is enabled by the C<"switch"> feature: see
-L<feature> for more information.  You can also access it by
-prefixing it with C<CORE::>.  Alternately, include a C<use
-v5.10> or later to the current scope.
-
-=item caller EXPR
-X<caller> X<call stack> X<stack> X<stack trace>
-
-=item caller
-
-Returns the context of the current subroutine call.  In scalar context,
-returns the caller's package name if there I<is> a caller (that is, if
-we're in a subroutine or C<eval> or C<require>) and the undefined value
-otherwise.  In list context, returns
-
-    # 0         1          2
-    ($package, $filename, $line) = caller;
-
-With EXPR, it returns some extra information that the debugger uses to
-print a stack trace.  The value of EXPR indicates how many call frames
-to go back before the current one.
-
-    #  0         1          2      3            4
-    ($package, $filename, $line, $subroutine, $hasargs,
-
-    #  5          6          7            8       9         10
-    $wantarray, $evaltext, $is_require, $hints, $bitmask, $hinthash)
-     = caller($i);
-
-Here $subroutine may be C<(eval)> if the frame is not a subroutine
-call, but an C<eval>.  In such a case additional elements $evaltext and
-C<$is_require> are set: C<$is_require> is true if the frame is created by a
-C<require> or C<use> statement, $evaltext contains the text of the
-C<eval EXPR> statement.  In particular, for an C<eval BLOCK> statement,
-$subroutine is C<(eval)>, but $evaltext is undefined.  (Note also that
-each C<use> statement creates a C<require> frame inside an C<eval EXPR>
-frame.)  $subroutine may also be C<(unknown)> if this particular
-subroutine happens to have been deleted from the symbol table.
-C<$hasargs> is true if a new instance of C<@_> was set up for the frame.
-C<$hints> and C<$bitmask> contain pragmatic hints that the caller was
-compiled with.  The C<$hints> and C<$bitmask> values are subject to change
-between versions of Perl, and are not meant for external use.
-
-C<$hinthash> is a reference to a hash containing the value of C<%^H> when the
-caller was compiled, or C<undef> if C<%^H> was empty. Do not modify the values
-of this hash, as they are the actual values stored in the optree.
-
-Furthermore, when called from within the DB package, caller returns more
-detailed information: it sets the list variable C<@DB::args> to be the
-arguments with which the subroutine was invoked.
-
-Be aware that the optimizer might have optimized call frames away before
-C<caller> had a chance to get the information.  That means that C<caller(N)>
-might not return information about the call frame you expect it to, for
-C<< N > 1 >>.  In particular, C<@DB::args> might have information from the
-previous time C<caller> was called.
-
-Be aware that setting C<@DB::args> is I<best effort>, intended for
-debugging or generating backtraces, and should not be relied upon. In
-particular, as C<@_> contains aliases to the caller's arguments, Perl does
-not take a copy of C<@_>, so C<@DB::args> will contain modifications the
-subroutine makes to C<@_> or its contents, not the original values at call
-time. C<@DB::args>, like C<@_>, does not hold explicit references to its
-elements, so under certain cases its elements may have become freed and
-reallocated for other variables or temporary values. Finally, a side effect
-of the current implementation is that the effects of C<shift @_> can
-I<normally> be undone (but not C<pop @_> or other splicing, I<and> not if a
-reference to C<@_> has been taken, I<and> subject to the caveat about reallocated
-elements), so C<@DB::args> is actually a hybrid of the current state and
-initial state of C<@_>. Buyer beware.
-
-=item chdir EXPR
-X<chdir>
-X<cd>
-X<directory, change>
-
-=item chdir FILEHANDLE
-
-=item chdir DIRHANDLE
-
-=item chdir
-
-Changes the working directory to EXPR, if possible. If EXPR is omitted,
-changes to the directory specified by C<$ENV{HOME}>, if set; if not,
-changes to the directory specified by C<$ENV{LOGDIR}>. (Under VMS, the
-variable C<$ENV{SYS$LOGIN}> is also checked, and used if it is set.) If
-neither is set, C<chdir> does nothing. It returns true on success,
-false otherwise. See the example under C<die>.
-
-On systems that support fchdir(2), you may pass a filehandle or
-directory handle as the argument.  On systems that don't support fchdir(2),
-passing handles raises an exception.
-
-=item chmod LIST
-X<chmod> X<permission> X<mode>
-
-Changes the permissions of a list of files.  The first element of the
-list must be the numeric mode, which should probably be an octal
-number, and which definitely should I<not> be a string of octal digits:
-C<0644> is okay, but C<"0644"> is not.  Returns the number of files
-successfully changed.  See also L</oct> if all you have is a string.
-
-    $cnt = chmod 0755, "foo", "bar";
-    chmod 0755, @executables;
-    $mode = "0644"; chmod $mode, "foo";      # !!! sets mode to
-                                             # --w----r-T
-    $mode = "0644"; chmod oct($mode), "foo"; # this is better
-    $mode = 0644;   chmod $mode, "foo";      # this is best
-
-On systems that support fchmod(2), you may pass filehandles among the
-files.  On systems that don't support fchmod(2), passing filehandles raises
-an exception.  Filehandles must be passed as globs or glob references to be
-recognized; barewords are considered filenames.
-
-    open(my $fh, "<", "foo");
-    my $perm = (stat $fh)[2] & 07777;
-    chmod($perm | 0600, $fh);
-
-You can also import the symbolic C<S_I*> constants from the C<Fcntl>
-module:
-
-    use Fcntl qw( :mode );
-    chmod S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH, @executables;
-    # Identical to the chmod 0755 of the example above.
-
-Portability issues: L<perlport/chmod>.
-
-=item chomp VARIABLE
-X<chomp> X<INPUT_RECORD_SEPARATOR> X<$/> X<newline> X<eol>
-
-=item chomp( LIST )
-
-=item chomp
-
-This safer version of L</chop> removes any trailing string
-that corresponds to the current value of C<$/> (also known as
-$INPUT_RECORD_SEPARATOR in the C<English> module).  It returns the total
-number of characters removed from all its arguments.  It's often used to
-remove the newline from the end of an input record when you're worried
-that the final record may be missing its newline.  When in paragraph
-mode (C<$/ = "">), it removes all trailing newlines from the string.
-When in slurp mode (C<$/ = undef>) or fixed-length record mode (C<$/> is
-a reference to an integer or the like; see L<perlvar>) chomp() won't
-remove anything.
-If VARIABLE is omitted, it chomps C<$_>.  Example:
-
-    while (<>) {
-        chomp;  # avoid \n on last field
-        @array = split(/:/);
-        # ...
-    }
-
-If VARIABLE is a hash, it chomps the hash's values, but not its keys.
-
-You can actually chomp anything that's an lvalue, including an assignment:
-
-    chomp($cwd = `pwd`);
-    chomp($answer = <STDIN>);
-
-If you chomp a list, each element is chomped, and the total number of
-characters removed is returned.
-
-Note that parentheses are necessary when you're chomping anything
-that is not a simple variable.  This is because C<chomp $cwd = `pwd`;>
-is interpreted as C<(chomp $cwd) = `pwd`;>, rather than as
-C<chomp( $cwd = `pwd` )> which you might expect.  Similarly,
-C<chomp $a, $b> is interpreted as C<chomp($a), $b> rather than
-as C<chomp($a, $b)>.
-
-=item chop VARIABLE
-X<chop>
-
-=item chop( LIST )
-
-=item chop
-
-Chops off the last character of a string and returns the character
-chopped.  It is much more efficient than C<s/.$//s> because it neither
-scans nor copies the string.  If VARIABLE is omitted, chops C<$_>.
-If VARIABLE is a hash, it chops the hash's values, but not its keys.
-
-You can actually chop anything that's an lvalue, including an assignment.
-
-If you chop a list, each element is chopped.  Only the value of the
-last C<chop> is returned.
-
-Note that C<chop> returns the last character.  To return all but the last
-character, use C<substr($string, 0, -1)>.
-
-See also L</chomp>.
-
-=item chown LIST
-X<chown> X<owner> X<user> X<group>
-
-Changes the owner (and group) of a list of files.  The first two
-elements of the list must be the I<numeric> uid and gid, in that
-order.  A value of -1 in either position is interpreted by most
-systems to leave that value unchanged.  Returns the number of files
-successfully changed.
-
-    $cnt = chown $uid, $gid, 'foo', 'bar';
-    chown $uid, $gid, @filenames;
-
-On systems that support fchown(2), you may pass filehandles among the
-files.  On systems that don't support fchown(2), passing filehandles raises
-an exception.  Filehandles must be passed as globs or glob references to be
-recognized; barewords are considered filenames.
-
-Here's an example that looks up nonnumeric uids in the passwd file:
-
-    print "User: ";
-    chomp($user = <STDIN>);
-    print "Files: ";
-    chomp($pattern = <STDIN>);
-
-    ($login,$pass,$uid,$gid) = getpwnam($user)
-        or die "$user not in passwd file";
-
-    @ary = glob($pattern);  # expand filenames
-    chown $uid, $gid, @ary;
-
-On most systems, you are not allowed to change the ownership of the
-file unless you're the superuser, although you should be able to change
-the group to any of your secondary groups.  On insecure systems, these
-restrictions may be relaxed, but this is not a portable assumption.
-On POSIX systems, you can detect this condition this way:
-
-    use POSIX qw(sysconf _PC_CHOWN_RESTRICTED);
-    $can_chown_giveaway = not sysconf(_PC_CHOWN_RESTRICTED);
-
-Portability issues: L<perlport/chmod>.
-
-=item chr NUMBER
-X<chr> X<character> X<ASCII> X<Unicode>
-
-=item chr
-
-Returns the character represented by that NUMBER in the character set.
-For example, C<chr(65)> is C<"A"> in either ASCII or Unicode, and
-chr(0x263a) is a Unicode smiley face.  
-
-Negative values give the Unicode replacement character (chr(0xfffd)),
-except under the L<bytes> pragma, where the low eight bits of the value
-(truncated to an integer) are used.
-
-If NUMBER is omitted, uses C<$_>.
-
-For the reverse, use L</ord>.
-
-Note that characters from 128 to 255 (inclusive) are by default
-internally not encoded as UTF-8 for backward compatibility reasons.
-
-See L<perlunicode> for more about Unicode.
-
-=item chroot FILENAME
-X<chroot> X<root>
-
-=item chroot
-
-This function works like the system call by the same name: it makes the
-named directory the new root directory for all further pathnames that
-begin with a C</> by your process and all its children.  (It doesn't
-change your current working directory, which is unaffected.)  For security
-reasons, this call is restricted to the superuser.  If FILENAME is
-omitted, does a C<chroot> to C<$_>.
-
-Portability issues: L<perlport/chroot>.
-
-=item close FILEHANDLE
-X<close>
-
-=item close
-
-Closes the file or pipe associated with the filehandle, flushes the IO
-buffers, and closes the system file descriptor.  Returns true if those
-operations succeed and if no error was reported by any PerlIO
-layer.  Closes the currently selected filehandle if the argument is
-omitted.
-
-You don't have to close FILEHANDLE if you are immediately going to do
-another C<open> on it, because C<open> closes it for you.  (See
-L<open|/open FILEHANDLE>.)  However, an explicit C<close> on an input file resets the line
-counter (C<$.>), while the implicit close done by C<open> does not.
-
-If the filehandle came from a piped open, C<close> returns false if one of
-the other syscalls involved fails or if its program exits with non-zero
-status.  If the only problem was that the program exited non-zero, C<$!>
-will be set to C<0>.  Closing a pipe also waits for the process executing
-on the pipe to exit--in case you wish to look at the output of the pipe
-afterwards--and implicitly puts the exit status value of that command into
-C<$?> and C<${^CHILD_ERROR_NATIVE}>.
-
-If there are multiple threads running, C<close> on a filehandle from a
-piped open returns true without waiting for the child process to terminate,
-if the filehandle is still open in another thread.
-
-Closing the read end of a pipe before the process writing to it at the
-other end is done writing results in the writer receiving a SIGPIPE.  If
-the other end can't handle that, be sure to read all the data before
-closing the pipe.
-
-Example:
-
-    open(OUTPUT, '|sort >foo')  # pipe to sort
-        or die "Can't start sort: $!";
-    #...                        # print stuff to output
-    close OUTPUT                # wait for sort to finish
-        or warn $! ? "Error closing sort pipe: $!"
-                   : "Exit status $? from sort";
-    open(INPUT, 'foo')          # get sort's results
-        or die "Can't open 'foo' for input: $!";
-
-FILEHANDLE may be an expression whose value can be used as an indirect
-filehandle, usually the real filehandle name or an autovivified handle.
-
-=item closedir DIRHANDLE
-X<closedir>
-
-Closes a directory opened by C<opendir> and returns the success of that
-system call.
-
-=item connect SOCKET,NAME
-X<connect>
-
-Attempts to connect to a remote socket, just like connect(2).
-Returns true if it succeeded, false otherwise.  NAME should be a
-packed address of the appropriate type for the socket.  See the examples in
-L<perlipc/"Sockets: Client/Server Communication">.
-
-=item continue BLOCK
-X<continue>
-
-=item continue
-
-When followed by a BLOCK, C<continue> is actually a
-flow control statement rather than a function.  If
-there is a C<continue> BLOCK attached to a BLOCK (typically in a C<while> or
-C<foreach>), it is always executed just before the conditional is about to
-be evaluated again, just like the third part of a C<for> loop in C.  Thus
-it can be used to increment a loop variable, even when the loop has been
-continued via the C<next> statement (which is similar to the C C<continue>
-statement).
-
-C<last>, C<next>, or C<redo> may appear within a C<continue>
-block; C<last> and C<redo> behave as if they had been executed within
-the main block.  So will C<next>, but since it will execute a C<continue>
-block, it may be more entertaining.
-
-    while (EXPR) {
-        ### redo always comes here
-        do_something;
-    } continue {
-        ### next always comes here
-        do_something_else;
-        # then back the top to re-check EXPR
-    }
-    ### last always comes here
-
-Omitting the C<continue> section is equivalent to using an
-empty one, logically enough, so C<next> goes directly back
-to check the condition at the top of the loop.
-
-When there is no BLOCK, C<continue> is a function that
-falls through the current C<when> or C<default> block instead of iterating
-a dynamically enclosing C<foreach> or exiting a lexically enclosing C<given>.
-In Perl 5.14 and earlier, this form of C<continue> was
-only available when the C<"switch"> feature was enabled.
-See L<feature> and L<perlsyn/"Switch statements"> for more
-information.
-
-=item cos EXPR
-X<cos> X<cosine> X<acos> X<arccosine>
-
-=item cos
-
-Returns the cosine of EXPR (expressed in radians).  If EXPR is omitted,
-takes the cosine of C<$_>.
-
-For the inverse cosine operation, you may use the C<Math::Trig::acos()>
-function, or use this relation:
-
-    sub acos { atan2( sqrt(1 - $_[0] * $_[0]), $_[0] ) }
-
-=item crypt PLAINTEXT,SALT
-X<crypt> X<digest> X<hash> X<salt> X<plaintext> X<password>
-X<decrypt> X<cryptography> X<passwd> X<encrypt>
-
-Creates a digest string exactly like the crypt(3) function in the C
-library (assuming that you actually have a version there that has not
-been extirpated as a potential munition).
-
-crypt() is a one-way hash function.  The PLAINTEXT and SALT are turned
-into a short string, called a digest, which is returned.  The same
-PLAINTEXT and SALT will always return the same string, but there is no
-(known) way to get the original PLAINTEXT from the hash.  Small
-changes in the PLAINTEXT or SALT will result in large changes in the
-digest.
-
-There is no decrypt function.  This function isn't all that useful for
-cryptography (for that, look for F<Crypt> modules on your nearby CPAN
-mirror) and the name "crypt" is a bit of a misnomer.  Instead it is
-primarily used to check if two pieces of text are the same without
-having to transmit or store the text itself.  An example is checking
-if a correct password is given.  The digest of the password is stored,
-not the password itself.  The user types in a password that is
-crypt()'d with the same salt as the stored digest.  If the two digests
-match, the password is correct.
-
-When verifying an existing digest string you should use the digest as
-the salt (like C<crypt($plain, $digest) eq $digest>).  The SALT used
-to create the digest is visible as part of the digest.  This ensures
-crypt() will hash the new string with the same salt as the digest.
-This allows your code to work with the standard L<crypt|/crypt> and
-with more exotic implementations.  In other words, assume
-nothing about the returned string itself nor about how many bytes 
-of SALT may matter.
-
-Traditionally the result is a string of 13 bytes: two first bytes of
-the salt, followed by 11 bytes from the set C<[./0-9A-Za-z]>, and only
-the first eight bytes of PLAINTEXT mattered. But alternative
-hashing schemes (like MD5), higher level security schemes (like C2),
-and implementations on non-Unix platforms may produce different
-strings.
-
-When choosing a new salt create a random two character string whose
-characters come from the set C<[./0-9A-Za-z]> (like C<join '', ('.',
-'/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]>).  This set of
-characters is just a recommendation; the characters allowed in
-the salt depend solely on your system's crypt library, and Perl can't
-restrict what salts C<crypt()> accepts.
-
-Here's an example that makes sure that whoever runs this program knows
-their password:
-
-    $pwd = (getpwuid($<))[1];
-
-    system "stty -echo";
-    print "Password: ";
-    chomp($word = <STDIN>);
-    print "\n";
-    system "stty echo";
-
-    if (crypt($word, $pwd) ne $pwd) {
-        die "Sorry...\n";
-    } else {
-        print "ok\n";
-    }
-
-Of course, typing in your own password to whoever asks you
-for it is unwise.
-
-The L<crypt|/crypt> function is unsuitable for hashing large quantities
-of data, not least of all because you can't get the information
-back.  Look at the L<Digest> module for more robust algorithms.
-
-If using crypt() on a Unicode string (which I<potentially> has
-characters with codepoints above 255), Perl tries to make sense
-of the situation by trying to downgrade (a copy of)
-the string back to an eight-bit byte string before calling crypt()
-(on that copy).  If that works, good.  If not, crypt() dies with
-C<Wide character in crypt>.
-
-Portability issues: L<perlport/crypt>.
-
-=item dbmclose HASH
-X<dbmclose>
-
-[This function has been largely superseded by the C<untie> function.]
-
-Breaks the binding between a DBM file and a hash.
-
-Portability issues: L<perlport/dbmclose>.
-
-=item dbmopen HASH,DBNAME,MASK
-X<dbmopen> X<dbm> X<ndbm> X<sdbm> X<gdbm>
-
-[This function has been largely superseded by the
-L<tie|/tie VARIABLE,CLASSNAME,LIST> function.]
-
-This binds a dbm(3), ndbm(3), sdbm(3), gdbm(3), or Berkeley DB file to a
-hash.  HASH is the name of the hash.  (Unlike normal C<open>, the first
-argument is I<not> a filehandle, even though it looks like one).  DBNAME
-is the name of the database (without the F<.dir> or F<.pag> extension if
-any).  If the database does not exist, it is created with protection
-specified by MASK (as modified by the C<umask>).  If your system supports
-only the older DBM functions, you may make only one C<dbmopen> call in your
-program.  In older versions of Perl, if your system had neither DBM nor
-ndbm, calling C<dbmopen> produced a fatal error; it now falls back to
-sdbm(3).
-
-If you don't have write access to the DBM file, you can only read hash
-variables, not set them.  If you want to test whether you can write,
-either use file tests or try setting a dummy hash entry inside an C<eval> 
-to trap the error.
-
-Note that functions such as C<keys> and C<values> may return huge lists
-when used on large DBM files.  You may prefer to use the C<each>
-function to iterate over large DBM files.  Example:
-
-    # print out history file offsets
-    dbmopen(%HIST,'/usr/lib/news/history',0666);
-    while (($key,$val) = each %HIST) {
-        print $key, ' = ', unpack('L',$val), "\n";
-    }
-    dbmclose(%HIST);
-
-See also L<AnyDBM_File> for a more general description of the pros and
-cons of the various dbm approaches, as well as L<DB_File> for a particularly
-rich implementation.
-
-You can control which DBM library you use by loading that library
-before you call dbmopen():
-
-    use DB_File;
-    dbmopen(%NS_Hist, "$ENV{HOME}/.netscape/history.db")
-        or die "Can't open netscape history file: $!";
-
-Portability issues: L<perlport/dbmopen>.
-
-=item default BLOCK
-
-Within a C<foreach> or a C<given>, a C<default> BLOCK acts like a C<when>
-that's always true.  Only available after Perl 5.10, and only if the
-C<switch> feature has been requested or if the keyword is prefixed with
-C<CORE::>.  See L</when>.
-
-=item defined EXPR
-X<defined> X<undef> X<undefined>
-
-=item defined
-
-Returns a Boolean value telling whether EXPR has a value other than
-the undefined value C<undef>.  If EXPR is not present, C<$_> is
-checked.
-
-Many operations return C<undef> to indicate failure, end of file,
-system error, uninitialized variable, and other exceptional
-conditions.  This function allows you to distinguish C<undef> from
-other values.  (A simple Boolean test will not distinguish among
-C<undef>, zero, the empty string, and C<"0">, which are all equally
-false.)  Note that since C<undef> is a valid scalar, its presence
-doesn't I<necessarily> indicate an exceptional condition: C<pop>
-returns C<undef> when its argument is an empty array, I<or> when the
-element to return happens to be C<undef>.
-
-You may also use C<defined(&func)> to check whether subroutine C<&func>
-has ever been defined.  The return value is unaffected by any forward
-declarations of C<&func>.  A subroutine that is not defined
-may still be callable: its package may have an C<AUTOLOAD> method that
-makes it spring into existence the first time that it is called; see
-L<perlsub>.
-
-Use of C<defined> on aggregates (hashes and arrays) is deprecated.  It
-used to report whether memory for that aggregate had ever been
-allocated.  This behavior may disappear in future versions of Perl.
-You should instead use a simple test for size:
-
-    if (@an_array) { print "has array elements\n" }
-    if (%a_hash)   { print "has hash members\n"   }
-
-When used on a hash element, it tells you whether the value is defined,
-not whether the key exists in the hash.  Use L</exists> for the latter
-purpose.
-
-Examples:
-
-    print if defined $switch{D};
-    print "$val\n" while defined($val = pop(@ary));
-    die "Can't readlink $sym: $!"
-        unless defined($value = readlink $sym);
-    sub foo { defined &$bar ? &$bar(@_) : die "No bar"; }
-    $debugging = 0 unless defined $debugging;
-
-Note:  Many folks tend to overuse C<defined> and are then surprised to
-discover that the number C<0> and C<""> (the zero-length string) are, in fact,
-defined values.  For example, if you say
-
-    "ab" =~ /a(.*)b/;
-
-The pattern match succeeds and C<$1> is defined, although it
-matched "nothing".  It didn't really fail to match anything.  Rather, it
-matched something that happened to be zero characters long.  This is all
-very above-board and honest.  When a function returns an undefined value,
-it's an admission that it couldn't give you an honest answer.  So you
-should use C<defined> only when questioning the integrity of what
-you're trying to do.  At other times, a simple comparison to C<0> or C<""> is
-what you want.
-
-See also L</undef>, L</exists>, L</ref>.
-
-=item delete EXPR
-X<delete>
-
-Given an expression that specifies an element or slice of a hash, C<delete>
-deletes the specified elements from that hash so that exists() on that element
-no longer returns true.  Setting a hash element to the undefined value does
-not remove its key, but deleting it does; see L</exists>.
-
-In list context, returns the value or values deleted, or the last such
-element in scalar context.  The return list's length always matches that of
-the argument list: deleting non-existent elements returns the undefined value
-in their corresponding positions.
-
-delete() may also be used on arrays and array slices, but its behavior is less
-straightforward.  Although exists() will return false for deleted entries,
-deleting array elements never changes indices of existing values; use shift()
-or splice() for that.  However, if all deleted elements fall at the end of an
-array, the array's size shrinks to the position of the highest element that
-still tests true for exists(), or to 0 if none do.
-
-B<WARNING:> Calling delete on array values is deprecated and likely to
-be removed in a future version of Perl.
-
-Deleting from C<%ENV> modifies the environment.  Deleting from a hash tied to
-a DBM file deletes the entry from the DBM file.  Deleting from a C<tied> hash
-or array may not necessarily return anything; it depends on the implementation
-of the C<tied> package's DELETE method, which may do whatever it pleases.
-
-The C<delete local EXPR> construct localizes the deletion to the current
-block at run time.  Until the block exits, elements locally deleted
-temporarily no longer exist.  See L<perlsub/"Localized deletion of elements
-of composite types">.
-
-    %hash = (foo => 11, bar => 22, baz => 33);
-    $scalar = delete $hash{foo};             # $scalar is 11
-    $scalar = delete @hash{qw(foo bar)};     # $scalar is 22
-    @array  = delete @hash{qw(foo bar baz)}; # @array  is (undef,undef,33)
-
-The following (inefficiently) deletes all the values of %HASH and @ARRAY:
-
-    foreach $key (keys %HASH) {
-        delete $HASH{$key};
-    }
-
-    foreach $index (0 .. $#ARRAY) {
-        delete $ARRAY[$index];
-    }
-
-And so do these:
-
-    delete @HASH{keys %HASH};
-
-    delete @ARRAY[0 .. $#ARRAY];
-
-But both are slower than assigning the empty list
-or undefining %HASH or @ARRAY, which is the customary 
-way to empty out an aggregate:
-
-    %HASH = ();     # completely empty %HASH
-    undef %HASH;    # forget %HASH ever existed
-
-    @ARRAY = ();    # completely empty @ARRAY
-    undef @ARRAY;   # forget @ARRAY ever existed
-
-The EXPR can be arbitrarily complicated provided its
-final operation is an element or slice of an aggregate:
-
-    delete $ref->[$x][$y]{$key};
-    delete @{$ref->[$x][$y]}{$key1, $key2, @morekeys};
-
-    delete $ref->[$x][$y][$index];
-    delete @{$ref->[$x][$y]}[$index1, $index2, @moreindices];
-
-=item die LIST
-X<die> X<throw> X<exception> X<raise> X<$@> X<abort>
-
-C<die> raises an exception. Inside an C<eval> the error message is stuffed
-into C<$@> and the C<eval> is terminated with the undefined value.
-If the exception is outside of all enclosing C<eval>s, then the uncaught
-exception prints LIST to C<STDERR> and exits with a non-zero value. If you
-need to exit the process with a specific exit code, see L</exit>.
-
-Equivalent examples:
-
-    die "Can't cd to spool: $!\n" unless chdir '/usr/spool/news';
-    chdir '/usr/spool/news' or die "Can't cd to spool: $!\n"
-
-If the last element of LIST does not end in a newline, the current
-script line number and input line number (if any) are also printed,
-and a newline is supplied.  Note that the "input line number" (also
-known as "chunk") is subject to whatever notion of "line" happens to
-be currently in effect, and is also available as the special variable
-C<$.>.  See L<perlvar/"$/"> and L<perlvar/"$.">.
-
-Hint: sometimes appending C<", stopped"> to your message will cause it
-to make better sense when the string C<"at foo line 123"> is appended.
-Suppose you are running script "canasta".
-
-    die "/etc/games is no good";
-    die "/etc/games is no good, stopped";
-
-produce, respectively
-
-    /etc/games is no good at canasta line 123.
-    /etc/games is no good, stopped at canasta line 123.
-
-If the output is empty and C<$@> already contains a value (typically from a
-previous eval) that value is reused after appending C<"\t...propagated">.
-This is useful for propagating exceptions:
-
-    eval { ... };
-    die unless $@ =~ /Expected exception/;
-
-If the output is empty and C<$@> contains an object reference that has a
-C<PROPAGATE> method, that method will be called with additional file
-and line number parameters.  The return value replaces the value in
-C<$@>;  i.e., as if C<< $@ = eval { $@->PROPAGATE(__FILE__, __LINE__) }; >>
-were called.
-
-If C<$@> is empty then the string C<"Died"> is used.
-
-If an uncaught exception results in interpreter exit, the exit code is
-determined from the values of C<$!> and C<$?> with this pseudocode:
-
-    exit $! if $!;              # errno
-    exit $? >> 8 if $? >> 8;    # child exit status
-    exit 255;                   # last resort
-
-The intent is to squeeze as much possible information about the likely cause
-into the limited space of the system exit code. However, as C<$!> is the value
-of C's C<errno>, which can be set by any system call, this means that the value
-of the exit code used by C<die> can be non-predictable, so should not be relied
-upon, other than to be non-zero.
-
-You can also call C<die> with a reference argument, and if this is trapped
-within an C<eval>, C<$@> contains that reference.  This permits more
-elaborate exception handling using objects that maintain arbitrary state
-about the exception.  Such a scheme is sometimes preferable to matching
-particular string values of C<$@> with regular expressions.  Because C<$@> 
-is a global variable and C<eval> may be used within object implementations,
-be careful that analyzing the error object doesn't replace the reference in
-the global variable.  It's easiest to make a local copy of the reference
-before any manipulations.  Here's an example:
-
-    use Scalar::Util "blessed";
-
-    eval { ... ; die Some::Module::Exception->new( FOO => "bar" ) };
-    if (my $ev_err = $@) {
-        if (blessed($ev_err) && $ev_err->isa("Some::Module::Exception")) {
-            # handle Some::Module::Exception
-        }
-        else {
-            # handle all other possible exceptions
-        }
-    }
-
-Because Perl stringifies uncaught exception messages before display,
-you'll probably want to overload stringification operations on
-exception objects.  See L<overload> for details about that.
-
-You can arrange for a callback to be run just before the C<die>
-does its deed, by setting the C<$SIG{__DIE__}> hook.  The associated
-handler is called with the error text and can change the error
-message, if it sees fit, by calling C<die> again.  See
-L<perlvar/%SIG> for details on setting C<%SIG> entries, and
-L<"eval BLOCK"> for some examples.  Although this feature was 
-to be run only right before your program was to exit, this is not
-currently so: the C<$SIG{__DIE__}> hook is currently called
-even inside eval()ed blocks/strings!  If one wants the hook to do
-nothing in such situations, put
-
-    die @_ if $^S;
-
-as the first line of the handler (see L<perlvar/$^S>).  Because
-this promotes strange action at a distance, this counterintuitive
-behavior may be fixed in a future release.
-
-See also exit(), warn(), and the Carp module.
-
-=item do BLOCK
-X<do> X<block>
-
-Not really a function.  Returns the value of the last command in the
-sequence of commands indicated by BLOCK.  When modified by the C<while> or
-C<until> loop modifier, executes the BLOCK once before testing the loop
-condition. (On other statements the loop modifiers test the conditional
-first.)
-
-C<do BLOCK> does I<not> count as a loop, so the loop control statements
-C<next>, C<last>, or C<redo> cannot be used to leave or restart the block.
-See L<perlsyn> for alternative strategies.
-
-=item do SUBROUTINE(LIST)
-X<do>
-
-This form of subroutine call is deprecated.  SUBROUTINE can be a bareword,
-a scalar variable or a subroutine beginning with C<&>.
-
-=item do EXPR
-X<do>
-
-Uses the value of EXPR as a filename and executes the contents of the
-file as a Perl script.
-
-    do 'stat.pl';
-
-is just like
-
-    eval `cat stat.pl`;
-
-except that it's more efficient and concise, keeps track of the current
-filename for error messages, searches the C<@INC> directories, and updates
-C<%INC> if the file is found.  See L<perlvar/@INC> and L<perlvar/%INC> for
-these variables.  It also differs in that code evaluated with C<do FILENAME>
-cannot see lexicals in the enclosing scope; C<eval STRING> does.  It's the
-same, however, in that it does reparse the file every time you call it,
-so you probably don't want to do this inside a loop.
-
-If C<do> can read the file but cannot compile it, it returns C<undef> and sets
-an error message in C<$@>.  If C<do> cannot read the file, it returns undef
-and sets C<$!> to the error.  Always check C<$@> first, as compilation
-could fail in a way that also sets C<$!>.  If the file is successfully
-compiled, C<do> returns the value of the last expression evaluated.
-
-Inclusion of library modules is better done with the
-C<use> and C<require> operators, which also do automatic error checking
-and raise an exception if there's a problem.
-
-You might like to use C<do> to read in a program configuration
-file.  Manual error checking can be done this way:
-
-    # read in config files: system first, then user
-    for $file ("/share/prog/defaults.rc",
-               "$ENV{HOME}/.someprogrc")
-    {
-        unless ($return = do $file) {
-            warn "couldn't parse $file: $@" if $@;
-            warn "couldn't do $file: $!"    unless defined $return;
-            warn "couldn't run $file"       unless $return;
-        }
-    }
-
-=item dump LABEL
-X<dump> X<core> X<undump>
-
-=item dump
-
-This function causes an immediate core dump.  See also the B<-u>
-command-line switch in L<perlrun>, which does the same thing.
-Primarily this is so that you can use the B<undump> program (not
-supplied) to turn your core dump into an executable binary after
-having initialized all your variables at the beginning of the
-program.  When the new binary is executed it will begin by executing
-a C<goto LABEL> (with all the restrictions that C<goto> suffers).
-Think of it as a goto with an intervening core dump and reincarnation.
-If C<LABEL> is omitted, restarts the program from the top.
-
-B<WARNING>: Any files opened at the time of the dump will I<not>
-be open any more when the program is reincarnated, with possible
-resulting confusion by Perl.
-
-This function is now largely obsolete, mostly because it's very hard to
-convert a core file into an executable. That's why you should now invoke
-it as C<CORE::dump()>, if you don't want to be warned against a possible
-typo.
-
-Portability issues: L<perlport/dump>.
-
-=item each HASH
-X<each> X<hash, iterator>
-
-=item each ARRAY
-X<array, iterator>
-
-=item each EXPR
-
-When called in list context, returns a 2-element list consisting of the key
-and value for the next element of a hash, or the index and value for the
-next element of an array, so that you can iterate over it.  When called in
-scalar context, returns only the key (not the value) in a hash, or the index
-in an array.
-
-Hash entries are returned in an apparently random order.  The actual random
-order is subject to change in future versions of Perl, but it is
-guaranteed to be in the same order as either the C<keys> or C<values>
-function would produce on the same (unmodified) hash.  Since Perl
-5.8.2 the ordering can be different even between different runs of Perl
-for security reasons (see L<perlsec/"Algorithmic Complexity Attacks">).
-
-After C<each> has returned all entries from the hash or array, the next
-call to C<each> returns the empty list in list context and C<undef> in
-scalar context.  The next call following that one restarts iteration.  Each
-hash or array has its own internal iterator, accessed by C<each>, C<keys>,
-and C<values>.  The iterator is implicitly reset when C<each> has reached
-the end as just described; it can be explicitly reset by calling C<keys> or
-C<values> on the hash or array.  If you add or delete a hash's elements
-while iterating over it, entries may be skipped or duplicated--so don't do
-that.  Exception: It is always safe to delete the item most recently
-returned by C<each()>, so the following code works properly:
-
-        while (($key, $value) = each %hash) {
-          print $key, "\n";
-          delete $hash{$key};   # This is safe
-        }
-
-This prints out your environment like the printenv(1) program,
-but in a different order:
-
-    while (($key,$value) = each %ENV) {
-        print "$key=$value\n";
-    }
-
-Starting with Perl 5.14, C<each> can take a scalar EXPR, which must hold
-reference to an unblessed hash or array.  The argument will be dereferenced
-automatically.  This aspect of C<each> is considered highly experimental.
-The exact behaviour may change in a future version of Perl.
-
-    while (($key,$value) = each $hashref) { ... }
-
-See also C<keys>, C<values>, and C<sort>.
-
-=item eof FILEHANDLE
-X<eof>
-X<end of file>
-X<end-of-file>
-
-=item eof ()
-
-=item eof
-
-Returns 1 if the next read on FILEHANDLE will return end of file I<or> if
-FILEHANDLE is not open.  FILEHANDLE may be an expression whose value
-gives the real filehandle.  (Note that this function actually
-reads a character and then C<ungetc>s it, so isn't useful in an
-interactive context.)  Do not read from a terminal file (or call
-C<eof(FILEHANDLE)> on it) after end-of-file is reached.  File types such
-as terminals may lose the end-of-file condition if you do.
-
-An C<eof> without an argument uses the last file read.  Using C<eof()>
-with empty parentheses is different.  It refers to the pseudo file
-formed from the files listed on the command line and accessed via the
-C<< <> >> operator.  Since C<< <> >> isn't explicitly opened,
-as a normal filehandle is, an C<eof()> before C<< <> >> has been
-used will cause C<@ARGV> to be examined to determine if input is
-available.   Similarly, an C<eof()> after C<< <> >> has returned
-end-of-file will assume you are processing another C<@ARGV> list,
-and if you haven't set C<@ARGV>, will read input from C<STDIN>;
-see L<perlop/"I/O Operators">.
-
-In a C<< while (<>) >> loop, C<eof> or C<eof(ARGV)> can be used to
-detect the end of each file, whereas C<eof()> will detect the end 
-of the very last file only.  Examples:
-
-    # reset line numbering on each input file
-    while (<>) {
-        next if /^\s*#/;  # skip comments
-        print "$.\t$_";
-    } continue {
-        close ARGV if eof;  # Not eof()!
-    }
-
-    # insert dashes just before last line of last file
-    while (<>) {
-        if (eof()) {  # check for end of last file
-            print "--------------\n";
-        }
-        print;
-        last if eof();      # needed if we're reading from a terminal
-    }
-
-Practical hint: you almost never need to use C<eof> in Perl, because the
-input operators typically return C<undef> when they run out of data or 
-encounter an error.
-
-=item eval EXPR
-X<eval> X<try> X<catch> X<evaluate> X<parse> X<execute>
-X<error, handling> X<exception, handling>
-
-=item eval BLOCK
-
-=item eval
-
-In the first form, the return value of EXPR is parsed and executed as if it
-were a little Perl program.  The value of the expression (which is itself
-determined within scalar context) is first parsed, and if there were no
-errors, executed as a block within the lexical context of the current Perl
-program.  This means, that in particular, any outer lexical variables are
-visible to it, and any package variable settings or subroutine and format
-definitions remain afterwards.
-
-Note that the value is parsed every time the C<eval> executes.
-If EXPR is omitted, evaluates C<$_>.  This form is typically used to
-delay parsing and subsequent execution of the text of EXPR until run time.
-
-If the C<unicode_eval> feature is enabled (which is the default under a
-C<use 5.16> or higher declaration), EXPR or C<$_> is treated as a string of
-characters, so C<use utf8> declarations have no effect, and source filters
-are forbidden.  In the absence of the C<unicode_eval> feature, the string
-will sometimes be treated as characters and sometimes as bytes, depending
-on the internal encoding, and source filters activated within the C<eval>
-exhibit the erratic, but historical, behaviour of affecting some outer file
-scope that is still compiling.  See also the L</evalbytes> keyword, which
-always treats its input as a byte stream and works properly with source
-filters, and the L<feature> pragma.
-
-In the second form, the code within the BLOCK is parsed only once--at the
-same time the code surrounding the C<eval> itself was parsed--and executed
-within the context of the current Perl program.  This form is typically
-used to trap exceptions more efficiently than the first (see below), while
-also providing the benefit of checking the code within BLOCK at compile
-time.
-
-The final semicolon, if any, may be omitted from the value of EXPR or within
-the BLOCK.
-
-In both forms, the value returned is the value of the last expression
-evaluated inside the mini-program; a return statement may be also used, just
-as with subroutines.  The expression providing the return value is evaluated
-in void, scalar, or list context, depending on the context of the C<eval> 
-itself.  See L</wantarray> for more on how the evaluation context can be 
-determined.
-
-If there is a syntax error or runtime error, or a C<die> statement is
-executed, C<eval> returns C<undef> in scalar context
-or an empty list--or, for syntax errors, a list containing a single
-undefined value--in list context, and C<$@> is set to the error
-message.  The discrepancy in the return values in list context is
-considered a bug by some, and will probably be fixed in a future
-release.  If there was no error, C<$@> is set to the empty string.  A
-control flow operator like C<last> or C<goto> can bypass the setting of
-C<$@>.  Beware that using C<eval> neither silences Perl from printing
-warnings to STDERR, nor does it stuff the text of warning messages into C<$@>.
-To do either of those, you have to use the C<$SIG{__WARN__}> facility, or
-turn off warnings inside the BLOCK or EXPR using S<C<no warnings 'all'>>.
-See L</warn>, L<perlvar>, L<warnings> and L<perllexwarn>.
-
-Note that, because C<eval> traps otherwise-fatal errors, it is useful for
-determining whether a particular feature (such as C<socket> or C<symlink>)
-is implemented.  It is also Perl's exception-trapping mechanism, where
-the die operator is used to raise exceptions.
-
-If you want to trap errors when loading an XS module, some problems with
-the binary interface (such as Perl version skew) may be fatal even with
-C<eval> unless C<$ENV{PERL_DL_NONLAZY}> is set.  See L<perlrun>.
-
-If the code to be executed doesn't vary, you may use the eval-BLOCK
-form to trap run-time errors without incurring the penalty of
-recompiling each time.  The error, if any, is still returned in C<$@>.
-Examples:
-
-    # make divide-by-zero nonfatal
-    eval { $answer = $a / $b; }; warn $@ if $@;
-
-    # same thing, but less efficient
-    eval '$answer = $a / $b'; warn $@ if $@;
-
-    # a compile-time error
-    eval { $answer = }; # WRONG
-
-    # a run-time error
-    eval '$answer =';   # sets $@
-
-Using the C<eval{}> form as an exception trap in libraries does have some
-issues.  Due to the current arguably broken state of C<__DIE__> hooks, you
-may wish not to trigger any C<__DIE__> hooks that user code may have installed.
-You can use the C<local $SIG{__DIE__}> construct for this purpose,
-as this example shows:
-
-    # a private exception trap for divide-by-zero
-    eval { local $SIG{'__DIE__'}; $answer = $a / $b; };
-    warn $@ if $@;
-
-This is especially significant, given that C<__DIE__> hooks can call
-C<die> again, which has the effect of changing their error messages:
-
-    # __DIE__ hooks may modify error messages
-    {
-       local $SIG{'__DIE__'} =
-              sub { (my $x = $_[0]) =~ s/foo/bar/g; die $x };
-       eval { die "foo lives here" };
-       print $@ if $@;                # prints "bar lives here"
-    }
-
-Because this promotes action at a distance, this counterintuitive behavior
-may be fixed in a future release.
-
-With an C<eval>, you should be especially careful to remember what's
-being looked at when:
-
-    eval $x;        # CASE 1
-    eval "$x";      # CASE 2
-
-    eval '$x';      # CASE 3
-    eval { $x };    # CASE 4
-
-    eval "\$$x++";  # CASE 5
-    $$x++;          # CASE 6
-
-Cases 1 and 2 above behave identically: they run the code contained in
-the variable $x.  (Although case 2 has misleading double quotes making
-the reader wonder what else might be happening (nothing is).)  Cases 3
-and 4 likewise behave in the same way: they run the code C<'$x'>, which
-does nothing but return the value of $x.  (Case 4 is preferred for
-purely visual reasons, but it also has the advantage of compiling at
-compile-time instead of at run-time.)  Case 5 is a place where
-normally you I<would> like to use double quotes, except that in this
-particular situation, you can just use symbolic references instead, as
-in case 6.
-
-Before Perl 5.14, the assignment to C<$@> occurred before restoration 
-of localised variables, which means that for your code to run on older
-versions, a temporary is required if you want to mask some but not all
-errors:
-
-    # alter $@ on nefarious repugnancy only
-    {
-       my $e;
-       {
-          local $@; # protect existing $@
-          eval { test_repugnancy() };
-          # $@ =~ /nefarious/ and die $@; # Perl 5.14 and higher only
-          $@ =~ /nefarious/ and $e = $@;
-       }
-       die $e if defined $e
-    }
-
-C<eval BLOCK> does I<not> count as a loop, so the loop control statements
-C<next>, C<last>, or C<redo> cannot be used to leave or restart the block.
-
-An C<eval ''> executed within the C<DB> package doesn't see the usual
-surrounding lexical scope, but rather the scope of the first non-DB piece
-of code that called it.  You don't normally need to worry about this unless
-you are writing a Perl debugger.
-
-=item evalbytes EXPR
-X<evalbytes>
-
-=item evalbytes
-
-This function is like L</eval> with a string argument, except it always
-parses its argument, or C<$_> if EXPR is omitted, as a string of bytes.  A
-string containing characters whose ordinal value exceeds 255 results in an
-error.  Source filters activated within the evaluated code apply to the
-code itself.
-
-This function is only available under the C<evalbytes> feature, a
-C<use v5.16> (or higher) declaration, or with a C<CORE::> prefix.  See
-L<feature> for more information.
-
-=item exec LIST
-X<exec> X<execute>
-
-=item exec PROGRAM LIST
-
-The C<exec> function executes a system command I<and never returns>;
-use C<system> instead of C<exec> if you want it to return.  It fails and
-returns false only if the command does not exist I<and> it is executed
-directly instead of via your system's command shell (see below).
-
-Since it's a common mistake to use C<exec> instead of C<system>, Perl
-warns you if there is a following statement that isn't C<die>, C<warn>,
-or C<exit> (if C<-w> is set--but you always do that, right?).   If you
-I<really> want to follow an C<exec> with some other statement, you
-can use one of these styles to avoid the warning:
-
-    exec ('foo')   or print STDERR "couldn't exec foo: $!";
-    { exec ('foo') }; print STDERR "couldn't exec foo: $!";
-
-If there is more than one argument in LIST, or if LIST is an array
-with more than one value, calls execvp(3) with the arguments in LIST.
-If there is only one scalar argument or an array with one element in it,
-the argument is checked for shell metacharacters, and if there are any,
-the entire argument is passed to the system's command shell for parsing
-(this is C</bin/sh -c> on Unix platforms, but varies on other platforms).
-If there are no shell metacharacters in the argument, it is split into
-words and passed directly to C<execvp>, which is more efficient.
-Examples:
-
-    exec '/bin/echo', 'Your arguments are: ', @ARGV;
-    exec "sort $outfile | uniq";
-
-If you don't really want to execute the first argument, but want to lie
-to the program you are executing about its own name, you can specify
-the program you actually want to run as an "indirect object" (without a
-comma) in front of the LIST.  (This always forces interpretation of the
-LIST as a multivalued list, even if there is only a single scalar in
-the list.)  Example:
-
-    $shell = '/bin/csh';
-    exec $shell '-sh';    # pretend it's a login shell
-
-or, more directly,
-
-    exec {'/bin/csh'} '-sh';  # pretend it's a login shell
-
-When the arguments get executed via the system shell, results are
-subject to its quirks and capabilities.  See L<perlop/"`STRING`">
-for details.
-
-Using an indirect object with C<exec> or C<system> is also more
-secure.  This usage (which also works fine with system()) forces
-interpretation of the arguments as a multivalued list, even if the
-list had just one argument.  That way you're safe from the shell
-expanding wildcards or splitting up words with whitespace in them.
-
-    @args = ( "echo surprise" );
-
-    exec @args;               # subject to shell escapes
-                                # if @args == 1
-    exec { $args[0] } @args;  # safe even with one-arg list
-
-The first version, the one without the indirect object, ran the I<echo>
-program, passing it C<"surprise"> an argument.  The second version didn't;
-it tried to run a program named I<"echo surprise">, didn't find it, and set
-C<$?> to a non-zero value indicating failure.
-
-Beginning with v5.6.0, Perl attempts to flush all files opened for
-output before the exec, but this may not be supported on some platforms
-(see L<perlport>).  To be safe, you may need to set C<$|> ($AUTOFLUSH
-in English) or call the C<autoflush()> method of C<IO::Handle> on any
-open handles to avoid lost output.
-
-Note that C<exec> will not call your C<END> blocks, nor will it invoke
-C<DESTROY> methods on your objects.
-
-Portability issues: L<perlport/exec>.
-
-=item exists EXPR
-X<exists> X<autovivification>
-
-Given an expression that specifies an element of a hash, returns true if the
-specified element in the hash has ever been initialized, even if the
-corresponding value is undefined.
-
-    print "Exists\n"    if exists $hash{$key};
-    print "Defined\n"   if defined $hash{$key};
-    print "True\n"      if $hash{$key};
-
-exists may also be called on array elements, but its behavior is much less
-obvious and is strongly tied to the use of L</delete> on arrays.  B<Be aware>
-that calling exists on array values is deprecated and likely to be removed in
-a future version of Perl.
-
-    print "Exists\n"    if exists $array[$index];
-    print "Defined\n"   if defined $array[$index];
-    print "True\n"      if $array[$index];
-
-A hash or array element can be true only if it's defined and defined only if
-it exists, but the reverse doesn't necessarily hold true.
-
-Given an expression that specifies the name of a subroutine,
-returns true if the specified subroutine has ever been declared, even
-if it is undefined.  Mentioning a subroutine name for exists or defined
-does not count as declaring it.  Note that a subroutine that does not
-exist may still be callable: its package may have an C<AUTOLOAD>
-method that makes it spring into existence the first time that it is
-called; see L<perlsub>.
-
-    print "Exists\n"  if exists &subroutine;
-    print "Defined\n" if defined &subroutine;
-
-Note that the EXPR can be arbitrarily complicated as long as the final
-operation is a hash or array key lookup or subroutine name:
-
-    if (exists $ref->{A}->{B}->{$key})  { }
-    if (exists $hash{A}{B}{$key})       { }
-
-    if (exists $ref->{A}->{B}->[$ix])   { }
-    if (exists $hash{A}{B}[$ix])        { }
-
-    if (exists &{$ref->{A}{B}{$key}})   { }
-
-Although the mostly deeply nested array or hash will not spring into
-existence just because its existence was tested, any intervening ones will.
-Thus C<< $ref->{"A"} >> and C<< $ref->{"A"}->{"B"} >> will spring
-into existence due to the existence test for the $key element above.
-This happens anywhere the arrow operator is used, including even here:
-
-    undef $ref;
-    if (exists $ref->{"Some key"})    { }
-    print $ref;  # prints HASH(0x80d3d5c)
-
-This surprising autovivification in what does not at first--or even
-second--glance appear to be an lvalue context may be fixed in a future
-release.
-
-Use of a subroutine call, rather than a subroutine name, as an argument
-to exists() is an error.
-
-    exists &sub;    # OK
-    exists &sub();  # Error
-
-=item exit EXPR
-X<exit> X<terminate> X<abort>
-
-=item exit
-
-Evaluates EXPR and exits immediately with that value.    Example:
-
-    $ans = <STDIN>;
-    exit 0 if $ans =~ /^[Xx]/;
-
-See also C<die>.  If EXPR is omitted, exits with C<0> status.  The only
-universally recognized values for EXPR are C<0> for success and C<1>
-for error; other values are subject to interpretation depending on the
-environment in which the Perl program is running.  For example, exiting
-69 (EX_UNAVAILABLE) from a I<sendmail> incoming-mail filter will cause
-the mailer to return the item undelivered, but that's not true everywhere.
-
-Don't use C<exit> to abort a subroutine if there's any chance that
-someone might want to trap whatever error happened.  Use C<die> instead,
-which can be trapped by an C<eval>.
-
-The exit() function does not always exit immediately.  It calls any
-defined C<END> routines first, but these C<END> routines may not
-themselves abort the exit.  Likewise any object destructors that need to
-be called are called before the real exit.  C<END> routines and destructors
-can change the exit status by modifying C<$?>. If this is a problem, you
-can call C<POSIX:_exit($status)> to avoid END and destructor processing.
-See L<perlmod> for details.
-
-Portability issues: L<perlport/exit>.
-
-=item exp EXPR
-X<exp> X<exponential> X<antilog> X<antilogarithm> X<e>
-
-=item exp
-
-Returns I<e> (the natural logarithm base) to the power of EXPR.
-If EXPR is omitted, gives C<exp($_)>.
-
-=item fcntl FILEHANDLE,FUNCTION,SCALAR
-X<fcntl>
-
-Implements the fcntl(2) function.  You'll probably have to say
-
-    use Fcntl;
-
-first to get the correct constant definitions.  Argument processing and
-value returned work just like C<ioctl> below.
-For example:
-
-    use Fcntl;
-    fcntl($filehandle, F_GETFL, $packed_return_buffer)
-        or die "can't fcntl F_GETFL: $!";
-
-You don't have to check for C<defined> on the return from C<fcntl>.
-Like C<ioctl>, it maps a C<0> return from the system call into
-C<"0 but true"> in Perl.  This string is true in boolean context and C<0>
-in numeric context.  It is also exempt from the normal B<-w> warnings
-on improper numeric conversions.
-
-Note that C<fcntl> raises an exception if used on a machine that
-doesn't implement fcntl(2).  See the Fcntl module or your fcntl(2)
-manpage to learn what functions are available on your system.
-
-Here's an example of setting a filehandle named C<REMOTE> to be
-non-blocking at the system level.  You'll have to negotiate C<$|>
-on your own, though.
-
-    use Fcntl qw(F_GETFL F_SETFL O_NONBLOCK);
-
-    $flags = fcntl(REMOTE, F_GETFL, 0)
-                or die "Can't get flags for the socket: $!\n";
-
-    $flags = fcntl(REMOTE, F_SETFL, $flags | O_NONBLOCK)
-                or die "Can't set flags for the socket: $!\n";
-
-Portability issues: L<perlport/fcntl>.
-
-=item __FILE__
-X<__FILE__>
-
-A special token that returns the name of the file in which it occurs.
-
-=item fileno FILEHANDLE
-X<fileno>
-
-Returns the file descriptor for a filehandle, or undefined if the
-filehandle is not open.  If there is no real file descriptor at the OS
-level, as can happen with filehandles connected to memory objects via
-C<open> with a reference for the third argument, -1 is returned.
-
-This is mainly useful for constructing
-bitmaps for C<select> and low-level POSIX tty-handling operations.
-If FILEHANDLE is an expression, the value is taken as an indirect
-filehandle, generally its name.
-
-You can use this to find out whether two handles refer to the
-same underlying descriptor:
-
-    if (fileno(THIS) == fileno(THAT)) {
-        print "THIS and THAT are dups\n";
-    }
-
-=item flock FILEHANDLE,OPERATION
-X<flock> X<lock> X<locking>
-
-Calls flock(2), or an emulation of it, on FILEHANDLE.  Returns true
-for success, false on failure.  Produces a fatal error if used on a
-machine that doesn't implement flock(2), fcntl(2) locking, or lockf(3).
-C<flock> is Perl's portable file-locking interface, although it locks
-entire files only, not records.
-
-Two potentially non-obvious but traditional C<flock> semantics are
-that it waits indefinitely until the lock is granted, and that its locks
-are B<merely advisory>.  Such discretionary locks are more flexible, but
-offer fewer guarantees.  This means that programs that do not also use
-C<flock> may modify files locked with C<flock>.  See L<perlport>, 
-your port's specific documentation, and your system-specific local manpages
-for details.  It's best to assume traditional behavior if you're writing
-portable programs.  (But if you're not, you should as always feel perfectly
-free to write for your own system's idiosyncrasies (sometimes called
-"features").  Slavish adherence to portability concerns shouldn't get
-in the way of your getting your job done.)
-
-OPERATION is one of LOCK_SH, LOCK_EX, or LOCK_UN, possibly combined with
-LOCK_NB.  These constants are traditionally valued 1, 2, 8 and 4, but
-you can use the symbolic names if you import them from the L<Fcntl> module,
-either individually, or as a group using the C<:flock> tag.  LOCK_SH
-requests a shared lock, LOCK_EX requests an exclusive lock, and LOCK_UN
-releases a previously requested lock.  If LOCK_NB is bitwise-or'ed with
-LOCK_SH or LOCK_EX, then C<flock> returns immediately rather than blocking
-waiting for the lock; check the return status to see if you got it.
-
-To avoid the possibility of miscoordination, Perl now flushes FILEHANDLE
-before locking or unlocking it.
-
-Note that the emulation built with lockf(3) doesn't provide shared
-locks, and it requires that FILEHANDLE be open with write intent.  These
-are the semantics that lockf(3) implements.  Most if not all systems
-implement lockf(3) in terms of fcntl(2) locking, though, so the
-differing semantics shouldn't bite too many people.
-
-Note that the fcntl(2) emulation of flock(3) requires that FILEHANDLE
-be open with read intent to use LOCK_SH and requires that it be open
-with write intent to use LOCK_EX.
-
-Note also that some versions of C<flock> cannot lock things over the
-network; you would need to use the more system-specific C<fcntl> for
-that.  If you like you can force Perl to ignore your system's flock(2)
-function, and so provide its own fcntl(2)-based emulation, by passing
-the switch C<-Ud_flock> to the F<Configure> program when you configure
-and build a new Perl.
-
-Here's a mailbox appender for BSD systems.
-
-    use Fcntl qw(:flock SEEK_END); # import LOCK_* and SEEK_END constants
-
-    sub lock {
-        my ($fh) = @_;
-        flock($fh, LOCK_EX) or die "Cannot lock mailbox - $!\n";
-
-        # and, in case someone appended while we were waiting...
-        seek($fh, 0, SEEK_END) or die "Cannot seek - $!\n";
-    }
-
-    sub unlock {
-        my ($fh) = @_;
-        flock($fh, LOCK_UN) or die "Cannot unlock mailbox - $!\n";
-    }
-
-    open(my $mbox, ">>", "/usr/spool/mail/$ENV{'USER'}")
-        or die "Can't open mailbox: $!";
-
-    lock($mbox);
-    print $mbox $msg,"\n\n";
-    unlock($mbox);
-
-On systems that support a real flock(2), locks are inherited across fork()
-calls, whereas those that must resort to the more capricious fcntl(2)
-function lose their locks, making it seriously harder to write servers.
-
-See also L<DB_File> for other flock() examples.
-
-Portability issues: L<perlport/flock>.
-
-=item fork
-X<fork> X<child> X<parent>
-
-Does a fork(2) system call to create a new process running the
-same program at the same point.  It returns the child pid to the
-parent process, C<0> to the child process, or C<undef> if the fork is
-unsuccessful.  File descriptors (and sometimes locks on those descriptors)
-are shared, while everything else is copied.  On most systems supporting
-fork(), great care has gone into making it extremely efficient (for
-example, using copy-on-write technology on data pages), making it the
-dominant paradigm for multitasking over the last few decades.
-
-Beginning with v5.6.0, Perl attempts to flush all files opened for
-output before forking the child process, but this may not be supported
-on some platforms (see L<perlport>).  To be safe, you may need to set
-C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method of
-C<IO::Handle> on any open handles to avoid duplicate output.
-
-If you C<fork> without ever waiting on your children, you will
-accumulate zombies.  On some systems, you can avoid this by setting
-C<$SIG{CHLD}> to C<"IGNORE">.  See also L<perlipc> for more examples of
-forking and reaping moribund children.
-
-Note that if your forked child inherits system file descriptors like
-STDIN and STDOUT that are actually connected by a pipe or socket, even
-if you exit, then the remote server (such as, say, a CGI script or a
-backgrounded job launched from a remote shell) won't think you're done.
-You should reopen those to F</dev/null> if it's any issue.
-
-On some platforms such as Windows, where the fork() system call is not available,
-Perl can be built to emulate fork() in the Perl interpreter. The emulation is designed to,
-at the level of the Perl program, be as compatible as possible with the "Unix" fork().
-However it has limitations that have to be considered in code intended to be portable.
-See L<perlfork> for more details.
-
-Portability issues: L<perlport/fork>.
-
-=item format
-X<format>
-
-Declare a picture format for use by the C<write> function.  For
-example:
-
-    format Something =
-        Test: @<<<<<<<< @||||| @>>>>>
-              $str,     $%,    '$' . int($num)
-    .
-
-    $str = "widget";
-    $num = $cost/$quantity;
-    $~ = 'Something';
-    write;
-
-See L<perlform> for many details and examples.
-
-=item formline PICTURE,LIST
-X<formline>
-
-This is an internal function used by C<format>s, though you may call it,
-too.  It formats (see L<perlform>) a list of values according to the
-contents of PICTURE, placing the output into the format output
-accumulator, C<$^A> (or C<$ACCUMULATOR> in English).
-Eventually, when a C<write> is done, the contents of
-C<$^A> are written to some filehandle.  You could also read C<$^A>
-and then set C<$^A> back to C<"">.  Note that a format typically
-does one C<formline> per line of form, but the C<formline> function itself
-doesn't care how many newlines are embedded in the PICTURE.  This means
-that the C<~> and C<~~> tokens treat the entire PICTURE as a single line.
-You may therefore need to use multiple formlines to implement a single
-record format, just like the C<format> compiler.
-
-Be careful if you put double quotes around the picture, because an C<@>
-character may be taken to mean the beginning of an array name.
-C<formline> always returns true.  See L<perlform> for other examples.
-
-If you are trying to use this instead of C<write> to capture the output,
-you may find it easier to open a filehandle to a scalar
-(C<< open $fh, ">", \$output >>) and write to that instead.
-
-=item getc FILEHANDLE
-X<getc> X<getchar> X<character> X<file, read>
-
-=item getc
-
-Returns the next character from the input file attached to FILEHANDLE,
-or the undefined value at end of file or if there was an error (in
-the latter case C<$!> is set).  If FILEHANDLE is omitted, reads from
-STDIN.  This is not particularly efficient.  However, it cannot be
-used by itself to fetch single characters without waiting for the user
-to hit enter.  For that, try something more like:
-
-    if ($BSD_STYLE) {
-        system "stty cbreak </dev/tty >/dev/tty 2>&1";
-    }
-    else {
-        system "stty", '-icanon', 'eol', "\001";
-    }
-
-    $key = getc(STDIN);
-
-    if ($BSD_STYLE) {
-        system "stty -cbreak </dev/tty >/dev/tty 2>&1";
-    }
-    else {
-        system 'stty', 'icanon', 'eol', '^@'; # ASCII NUL
-    }
-    print "\n";
-
-Determination of whether $BSD_STYLE should be set
-is left as an exercise to the reader.
-
-The C<POSIX::getattr> function can do this more portably on
-systems purporting POSIX compliance.  See also the C<Term::ReadKey>
-module from your nearest CPAN site; details on CPAN can be found under
-L<perlmodlib/CPAN>.
-
-=item getlogin
-X<getlogin> X<login>
-
-This implements the C library function of the same name, which on most
-systems returns the current login from F</etc/utmp>, if any.  If it
-returns the empty string, use C<getpwuid>.
-
-    $login = getlogin || getpwuid($<) || "Kilroy";
-
-Do not consider C<getlogin> for authentication: it is not as
-secure as C<getpwuid>.
-
-Portability issues: L<perlport/getlogin>.
-
-=item getpeername SOCKET
-X<getpeername> X<peer>
-
-Returns the packed sockaddr address of the other end of the SOCKET
-connection.
-
-    use Socket;
-    $hersockaddr    = getpeername(SOCK);
-    ($port, $iaddr) = sockaddr_in($hersockaddr);
-    $herhostname    = gethostbyaddr($iaddr, AF_INET);
-    $herstraddr     = inet_ntoa($iaddr);
-
-=item getpgrp PID
-X<getpgrp> X<group>
-
-Returns the current process group for the specified PID.  Use
-a PID of C<0> to get the current process group for the
-current process.  Will raise an exception if used on a machine that
-doesn't implement getpgrp(2).  If PID is omitted, returns the process
-group of the current process.  Note that the POSIX version of C<getpgrp>
-does not accept a PID argument, so only C<PID==0> is truly portable.
-
-Portability issues: L<perlport/getpgrp>.
-
-=item getppid
-X<getppid> X<parent> X<pid>
-
-Returns the process id of the parent process.
-
-Note for Linux users: on Linux, the C functions C<getpid()> and
-C<getppid()> return different values from different threads. In order to
-be portable, this behavior is not reflected by the Perl-level function
-C<getppid()>, that returns a consistent value across threads. If you want
-to call the underlying C<getppid()>, you may use the CPAN module
-C<Linux::Pid>.
-
-Portability issues: L<perlport/getppid>.
-
-=item getpriority WHICH,WHO
-X<getpriority> X<priority> X<nice>
-
-Returns the current priority for a process, a process group, or a user.
-(See L<getpriority(2)>.)  Will raise a fatal exception if used on a
-machine that doesn't implement getpriority(2).
-
-Portability issues: L<perlport/getpriority>.
-
-=item getpwnam NAME
-X<getpwnam> X<getgrnam> X<gethostbyname> X<getnetbyname> X<getprotobyname>
-X<getpwuid> X<getgrgid> X<getservbyname> X<gethostbyaddr> X<getnetbyaddr>
-X<getprotobynumber> X<getservbyport> X<getpwent> X<getgrent> X<gethostent>
-X<getnetent> X<getprotoent> X<getservent> X<setpwent> X<setgrent> X<sethostent>
-X<setnetent> X<setprotoent> X<setservent> X<endpwent> X<endgrent> X<endhostent>
-X<endnetent> X<endprotoent> X<endservent> 
-
-=item getgrnam NAME
-
-=item gethostbyname NAME
-
-=item getnetbyname NAME
-
-=item getprotobyname NAME
-
-=item getpwuid UID
-
-=item getgrgid GID
-
-=item getservbyname NAME,PROTO
-
-=item gethostbyaddr ADDR,ADDRTYPE
-
-=item getnetbyaddr ADDR,ADDRTYPE
-
-=item getprotobynumber NUMBER
-
-=item getservbyport PORT,PROTO
-
-=item getpwent
-
-=item getgrent
-
-=item gethostent
-
-=item getnetent
-
-=item getprotoent
-
-=item getservent
-
-=item setpwent
-
-=item setgrent
-
-=item sethostent STAYOPEN
-
-=item setnetent STAYOPEN
-
-=item setprotoent STAYOPEN
-
-=item setservent STAYOPEN
-
-=item endpwent
-
-=item endgrent
-
-=item endhostent
-
-=item endnetent
-
-=item endprotoent
-
-=item endservent
-
-These routines are the same as their counterparts in the
-system C library.  In list context, the return values from the
-various get routines are as follows:
-
-    ($name,$passwd,$uid,$gid,
-       $quota,$comment,$gcos,$dir,$shell,$expire) = getpw*
-    ($name,$passwd,$gid,$members) = getgr*
-    ($name,$aliases,$addrtype,$length,@addrs) = gethost*
-    ($name,$aliases,$addrtype,$net) = getnet*
-    ($name,$aliases,$proto) = getproto*
-    ($name,$aliases,$port,$proto) = getserv*
-
-(If the entry doesn't exist you get an empty list.)
-
-The exact meaning of the $gcos field varies but it usually contains
-the real name of the user (as opposed to the login name) and other
-information pertaining to the user.  Beware, however, that in many
-system users are able to change this information and therefore it
-cannot be trusted and therefore the $gcos is tainted (see
-L<perlsec>).  The $passwd and $shell, user's encrypted password and
-login shell, are also tainted, for the same reason.
-
-In scalar context, you get the name, unless the function was a
-lookup by name, in which case you get the other thing, whatever it is.
-(If the entry doesn't exist you get the undefined value.)  For example:
-
-    $uid   = getpwnam($name);
-    $name  = getpwuid($num);
-    $name  = getpwent();
-    $gid   = getgrnam($name);
-    $name  = getgrgid($num);
-    $name  = getgrent();
-    #etc.
-
-In I<getpw*()> the fields $quota, $comment, and $expire are special
-in that they are unsupported on many systems.  If the
-$quota is unsupported, it is an empty scalar.  If it is supported, it
-usually encodes the disk quota.  If the $comment field is unsupported,
-it is an empty scalar.  If it is supported it usually encodes some
-administrative comment about the user.  In some systems the $quota
-field may be $change or $age, fields that have to do with password
-aging.  In some systems the $comment field may be $class.  The $expire
-field, if present, encodes the expiration period of the account or the
-password.  For the availability and the exact meaning of these fields
-in your system, please consult getpwnam(3) and your system's 
-F<pwd.h> file.  You can also find out from within Perl what your
-$quota and $comment fields mean and whether you have the $expire field
-by using the C<Config> module and the values C<d_pwquota>, C<d_pwage>,
-C<d_pwchange>, C<d_pwcomment>, and C<d_pwexpire>.  Shadow password
-files are supported only if your vendor has implemented them in the
-intuitive fashion that calling the regular C library routines gets the
-shadow versions if you're running under privilege or if there exists
-the shadow(3) functions as found in System V (this includes Solaris
-and Linux).  Those systems that implement a proprietary shadow password
-facility are unlikely to be supported.
-
-The $members value returned by I<getgr*()> is a space-separated list of
-the login names of the members of the group.
-
-For the I<gethost*()> functions, if the C<h_errno> variable is supported in
-C, it will be returned to you via C<$?> if the function call fails.  The
-C<@addrs> value returned by a successful call is a list of raw
-addresses returned by the corresponding library call.  In the
-Internet domain, each address is four bytes long; you can unpack it
-by saying something like:
-
-    ($a,$b,$c,$d) = unpack('W4',$addr[0]);
-
-The Socket library makes this slightly easier:
-
-    use Socket;
-    $iaddr = inet_aton("127.1"); # or whatever address
-    $name  = gethostbyaddr($iaddr, AF_INET);
-
-    # or going the other way
-    $straddr = inet_ntoa($iaddr);
-
-In the opposite way, to resolve a hostname to the IP address
-you can write this:
-
-    use Socket;
-    $packed_ip = gethostbyname("www.perl.org");
-    if (defined $packed_ip) {
-        $ip_address = inet_ntoa($packed_ip);
-    }
-
-Make sure C<gethostbyname()> is called in SCALAR context and that
-its return value is checked for definedness.
-
-The C<getprotobynumber> function, even though it only takes one argument,
-has the precedence of a list operator, so beware:
-
-    getprotobynumber $number eq 'icmp'   # WRONG
-    getprotobynumber($number eq 'icmp')  # actually means this
-    getprotobynumber($number) eq 'icmp'  # better this way
-
-If you get tired of remembering which element of the return list
-contains which return value, by-name interfaces are provided
-in standard modules: C<File::stat>, C<Net::hostent>, C<Net::netent>,
-C<Net::protoent>, C<Net::servent>, C<Time::gmtime>, C<Time::localtime>,
-and C<User::grent>.  These override the normal built-ins, supplying
-versions that return objects with the appropriate names
-for each field.  For example:
-
-   use File::stat;
-   use User::pwent;
-   $is_his = (stat($filename)->uid == pwent($whoever)->uid);
-
-Even though it looks as though they're the same method calls (uid),
-they aren't, because a C<File::stat> object is different from
-a C<User::pwent> object.
-
-Portability issues: L<perlport/getpwnam> to L<perlport/endservent>.
-
-=item getsockname SOCKET
-X<getsockname>
-
-Returns the packed sockaddr address of this end of the SOCKET connection,
-in case you don't know the address because you have several different
-IPs that the connection might have come in on.
-
-    use Socket;
-    $mysockaddr = getsockname(SOCK);
-    ($port, $myaddr) = sockaddr_in($mysockaddr);
-    printf "Connect to %s [%s]\n",
-       scalar gethostbyaddr($myaddr, AF_INET),
-       inet_ntoa($myaddr);
-
-=item getsockopt SOCKET,LEVEL,OPTNAME
-X<getsockopt>
-
-Queries the option named OPTNAME associated with SOCKET at a given LEVEL.
-Options may exist at multiple protocol levels depending on the socket
-type, but at least the uppermost socket level SOL_SOCKET (defined in the
-C<Socket> module) will exist. To query options at another level the
-protocol number of the appropriate protocol controlling the option
-should be supplied. For example, to indicate that an option is to be
-interpreted by the TCP protocol, LEVEL should be set to the protocol
-number of TCP, which you can get using C<getprotobyname>.
-
-The function returns a packed string representing the requested socket
-option, or C<undef> on error, with the reason for the error placed in
-C<$!>. Just what is in the packed string depends on LEVEL and OPTNAME;
-consult getsockopt(2) for details.  A common case is that the option is an
-integer, in which case the result is a packed integer, which you can decode
-using C<unpack> with the C<i> (or C<I>) format.
-
-Here's an example to test whether Nagle's algorithm is enabled on a socket:
-
-    use Socket qw(:all);
-
-    defined(my $tcp = getprotobyname("tcp"))
-        or die "Could not determine the protocol number for tcp";
-    # my $tcp = IPPROTO_TCP; # Alternative
-    my $packed = getsockopt($socket, $tcp, TCP_NODELAY)
-        or die "getsockopt TCP_NODELAY: $!";
-    my $nodelay = unpack("I", $packed);
-    print "Nagle's algorithm is turned ", $nodelay ? "off\n" : "on\n";
-
-Portability issues: L<perlport/getsockopt>.
-
-=item given EXPR BLOCK
-X<given>
-
-=item given BLOCK
-
-C<given> is analogous to the C<switch> keyword in other languages. C<given>
-and C<when> are used in Perl to implement C<switch>/C<case> like statements.
-Only available after Perl 5.10.  For example:
-
-    use v5.10;
-    given ($fruit) {
-        when (/apples?/) {
-            print "I like apples."
-        }
-        when (/oranges?/) {
-            print "I don't like oranges."
-        }
-        default {
-            print "I don't like anything"
-        }
-    }
-
-See L<perlsyn/"Switch statements"> for detailed information.
-
-=item glob EXPR
-X<glob> X<wildcard> X<filename, expansion> X<expand>
-
-=item glob
-
-In list context, returns a (possibly empty) list of filename expansions on
-the value of EXPR such as the standard Unix shell F</bin/csh> would do. In
-scalar context, glob iterates through such filename expansions, returning
-undef when the list is exhausted. This is the internal function
-implementing the C<< <*.c> >> operator, but you can use it directly. If
-EXPR is omitted, C<$_> is used.  The C<< <*.c> >> operator is discussed in
-more detail in L<perlop/"I/O Operators">.
-
-Note that C<glob> splits its arguments on whitespace and treats
-each segment as separate pattern.  As such, C<glob("*.c *.h")> 
-matches all files with a F<.c> or F<.h> extension.  The expression
-C<glob(".* *")> matches all files in the current working directory.
-If you want to glob filenames that might contain whitespace, you'll
-have to use extra quotes around the spacey filename to protect it.
-For example, to glob filenames that have an C<e> followed by a space
-followed by an C<f>, use either of:
-
-    @spacies = <"*e f*">;
-    @spacies = glob '"*e f*"';
-    @spacies = glob q("*e f*");
-
-If you had to get a variable through, you could do this:
-
-    @spacies = glob "'*${var}e f*'";
-    @spacies = glob qq("*${var}e f*");
-
-If non-empty braces are the only wildcard characters used in the
-C<glob>, no filenames are matched, but potentially many strings
-are returned.  For example, this produces nine strings, one for
-each pairing of fruits and colors:
-
-    @many =  glob "{apple,tomato,cherry}={green,yellow,red}";
-
-Beginning with v5.6.0, this operator is implemented using the standard
-C<File::Glob> extension.  See L<File::Glob> for details, including
-C<bsd_glob> which does not treat whitespace as a pattern separator.
-
-Portability issues: L<perlport/glob>.
-
-=item gmtime EXPR
-X<gmtime> X<UTC> X<Greenwich>
-
-=item gmtime
-
-Works just like L</localtime> but the returned values are
-localized for the standard Greenwich time zone.
-
-Note: When called in list context, $isdst, the last value
-returned by gmtime, is always C<0>.  There is no
-Daylight Saving Time in GMT.
-
-Portability issues: L<perlport/gmtime>.
-
-=item goto LABEL
-X<goto> X<jump> X<jmp>
-
-=item goto EXPR
-
-=item goto &NAME
-
-The C<goto-LABEL> form finds the statement labeled with LABEL and
-resumes execution there. It can't be used to get out of a block or
-subroutine given to C<sort>.  It can be used to go almost anywhere
-else within the dynamic scope, including out of subroutines, but it's
-usually better to use some other construct such as C<last> or C<die>.
-The author of Perl has never felt the need to use this form of C<goto>
-(in Perl, that is; C is another matter).  (The difference is that C
-does not offer named loops combined with loop control.  Perl does, and
-this replaces most structured uses of C<goto> in other languages.)
-
-The C<goto-EXPR> form expects a label name, whose scope will be resolved
-dynamically.  This allows for computed C<goto>s per FORTRAN, but isn't
-necessarily recommended if you're optimizing for maintainability:
-
-    goto ("FOO", "BAR", "GLARCH")[$i];
-
-As shown in this example, C<goto-EXPR> is exempt from the "looks like a
-function" rule. A pair of parentheses following it does not (necessarily)
-delimit its argument. C<goto("NE")."XT"> is equivalent to C<goto NEXT>.
-
-Use of C<goto-LABEL> or C<goto-EXPR> to jump into a construct is
-deprecated and will issue a warning.  Even then, it may not be used to
-go into any construct that requires initialization, such as a
-subroutine or a C<foreach> loop.  It also can't be used to go into a
-construct that is optimized away.
-
-The C<goto-&NAME> form is quite different from the other forms of
-C<goto>.  In fact, it isn't a goto in the normal sense at all, and
-doesn't have the stigma associated with other gotos.  Instead, it
-exits the current subroutine (losing any changes set by local()) and
-immediately calls in its place the named subroutine using the current
-value of @_.  This is used by C<AUTOLOAD> subroutines that wish to
-load another subroutine and then pretend that the other subroutine had
-been called in the first place (except that any modifications to C<@_>
-in the current subroutine are propagated to the other subroutine.)
-After the C<goto>, not even C<caller> will be able to tell that this
-routine was called first.
-
-NAME needn't be the name of a subroutine; it can be a scalar variable
-containing a code reference or a block that evaluates to a code
-reference.
-
-=item grep BLOCK LIST
-X<grep>
-
-=item grep EXPR,LIST
-
-This is similar in spirit to, but not the same as, grep(1) and its
-relatives.  In particular, it is not limited to using regular expressions.
-
-Evaluates the BLOCK or EXPR for each element of LIST (locally setting
-C<$_> to each element) and returns the list value consisting of those
-elements for which the expression evaluated to true.  In scalar
-context, returns the number of times the expression was true.
-
-    @foo = grep(!/^#/, @bar);    # weed out comments
-
-or equivalently,
-
-    @foo = grep {!/^#/} @bar;    # weed out comments
-
-Note that C<$_> is an alias to the list value, so it can be used to
-modify the elements of the LIST.  While this is useful and supported,
-it can cause bizarre results if the elements of LIST are not variables.
-Similarly, grep returns aliases into the original list, much as a for
-loop's index variable aliases the list elements.  That is, modifying an
-element of a list returned by grep (for example, in a C<foreach>, C<map>
-or another C<grep>) actually modifies the element in the original list.
-This is usually something to be avoided when writing clear code.
-
-If C<$_> is lexical in the scope where the C<grep> appears (because it has
-been declared with C<my $_>) then, in addition to being locally aliased to
-the list elements, C<$_> keeps being lexical inside the block; i.e., it
-can't be seen from the outside, avoiding any potential side-effects.
-
-See also L</map> for a list composed of the results of the BLOCK or EXPR.
-
-=item hex EXPR
-X<hex> X<hexadecimal>
-
-=item hex
-
-Interprets EXPR as a hex string and returns the corresponding value.
-(To convert strings that might start with either C<0>, C<0x>, or C<0b>, see
-L</oct>.)  If EXPR is omitted, uses C<$_>.
-
-    print hex '0xAf'; # prints '175'
-    print hex 'aF';   # same
-
-Hex strings may only represent integers.  Strings that would cause
-integer overflow trigger a warning.  Leading whitespace is not stripped,
-unlike oct(). To present something as hex, look into L</printf>,
-L</sprintf>, and L</unpack>.
-
-=item import LIST
-X<import>
-
-There is no builtin C<import> function.  It is just an ordinary
-method (subroutine) defined (or inherited) by modules that wish to export
-names to another module.  The C<use> function calls the C<import> method
-for the package used.  See also L</use>, L<perlmod>, and L<Exporter>.
-
-=item index STR,SUBSTR,POSITION
-X<index> X<indexOf> X<InStr>
-
-=item index STR,SUBSTR
-
-The index function searches for one string within another, but without
-the wildcard-like behavior of a full regular-expression pattern match.
-It returns the position of the first occurrence of SUBSTR in STR at
-or after POSITION.  If POSITION is omitted, starts searching from the
-beginning of the string.  POSITION before the beginning of the string
-or after its end is treated as if it were the beginning or the end,
-respectively.  POSITION and the return value are based at zero.
-If the substring is not found, C<index> returns -1.
-
-=item int EXPR
-X<int> X<integer> X<truncate> X<trunc> X<floor>
-
-=item int
-
-Returns the integer portion of EXPR.  If EXPR is omitted, uses C<$_>.
-You should not use this function for rounding: one because it truncates
-towards C<0>, and two because machine representations of floating-point
-numbers can sometimes produce counterintuitive results.  For example,
-C<int(-6.725/0.025)> produces -268 rather than the correct -269; that's
-because it's really more like -268.99999999999994315658 instead.  Usually,
-the C<sprintf>, C<printf>, or the C<POSIX::floor> and C<POSIX::ceil>
-functions will serve you better than will int().
-
-=item ioctl FILEHANDLE,FUNCTION,SCALAR
-X<ioctl>
-
-Implements the ioctl(2) function.  You'll probably first have to say
-
-    require "sys/ioctl.ph";  # probably in $Config{archlib}/sys/ioctl.ph
-
-to get the correct function definitions.  If F<sys/ioctl.ph> doesn't
-exist or doesn't have the correct definitions you'll have to roll your
-own, based on your C header files such as F<< <sys/ioctl.h> >>.
-(There is a Perl script called B<h2ph> that comes with the Perl kit that
-may help you in this, but it's nontrivial.)  SCALAR will be read and/or
-written depending on the FUNCTION; a C pointer to the string value of SCALAR
-will be passed as the third argument of the actual C<ioctl> call.  (If SCALAR
-has no string value but does have a numeric value, that value will be
-passed rather than a pointer to the string value.  To guarantee this to be
-true, add a C<0> to the scalar before using it.)  The C<pack> and C<unpack>
-functions may be needed to manipulate the values of structures used by
-C<ioctl>.
-
-The return value of C<ioctl> (and C<fcntl>) is as follows:
-
-    if OS returns:      then Perl returns:
-        -1               undefined value
-         0              string "0 but true"
-    anything else           that number
-
-Thus Perl returns true on success and false on failure, yet you can
-still easily determine the actual value returned by the operating
-system:
-
-    $retval = ioctl(...) || -1;
-    printf "System returned %d\n", $retval;
-
-The special string C<"0 but true"> is exempt from B<-w> complaints
-about improper numeric conversions.
-
-Portability issues: L<perlport/ioctl>.
-
-=item join EXPR,LIST
-X<join>
-
-Joins the separate strings of LIST into a single string with fields
-separated by the value of EXPR, and returns that new string.  Example:
-
-    $rec = join(':', $login,$passwd,$uid,$gid,$gcos,$home,$shell);
-
-Beware that unlike C<split>, C<join> doesn't take a pattern as its
-first argument.  Compare L</split>.
-
-=item keys HASH
-X<keys> X<key>
-
-=item keys ARRAY
-
-=item keys EXPR
-
-Returns a list consisting of all the keys of the named hash, or the indices
-of an array. (In scalar context, returns the number of keys or indices.)
-
-The keys of a hash are returned in an apparently random order.  The actual
-random order is subject to change in future versions of Perl, but it
-is guaranteed to be the same order as either the C<values> or C<each>
-function produces (given that the hash has not been modified).  Since
-Perl 5.8.1 the ordering can be different even between different runs of
-Perl for security reasons (see L<perlsec/"Algorithmic Complexity
-Attacks">).
-
-As a side effect, calling keys() resets the internal interator of the HASH or ARRAY
-(see L</each>).  In particular, calling keys() in void context resets
-the iterator with no other overhead.
-
-Here is yet another way to print your environment:
-
-    @keys = keys %ENV;
-    @values = values %ENV;
-    while (@keys) {
-        print pop(@keys), '=', pop(@values), "\n";
-    }
-
-or how about sorted by key:
-
-    foreach $key (sort(keys %ENV)) {
-        print $key, '=', $ENV{$key}, "\n";
-    }
-
-The returned values are copies of the original keys in the hash, so
-modifying them will not affect the original hash.  Compare L</values>.
-
-To sort a hash by value, you'll need to use a C<sort> function.
-Here's a descending numeric sort of a hash by its values:
-
-    foreach $key (sort { $hash{$b} <=> $hash{$a} } keys %hash) {
-        printf "%4d %s\n", $hash{$key}, $key;
-    }
-
-Used as an lvalue, C<keys> allows you to increase the number of hash buckets
-allocated for the given hash.  This can gain you a measure of efficiency if
-you know the hash is going to get big.  (This is similar to pre-extending
-an array by assigning a larger number to $#array.)  If you say
-
-    keys %hash = 200;
-
-then C<%hash> will have at least 200 buckets allocated for it--256 of them,
-in fact, since it rounds up to the next power of two.  These
-buckets will be retained even if you do C<%hash = ()>, use C<undef
-%hash> if you want to free the storage while C<%hash> is still in scope.
-You can't shrink the number of buckets allocated for the hash using
-C<keys> in this way (but you needn't worry about doing this by accident,
-as trying has no effect). C<keys @array> in an lvalue context is a syntax
-error.
-
-Starting with Perl 5.14, C<keys> can take a scalar EXPR, which must contain
-a reference to an unblessed hash or array.  The argument will be
-dereferenced automatically.  This aspect of C<keys> is considered highly
-experimental.  The exact behaviour may change in a future version of Perl.
-
-    for (keys $hashref) { ... }
-    for (keys $obj->get_arrayref) { ... }
-
-See also C<each>, C<values>, and C<sort>.
-
-=item kill SIGNAL, LIST
-X<kill> X<signal>
-
-Sends a signal to a list of processes.  Returns the number of
-processes successfully signaled (which is not necessarily the
-same as the number actually killed).
-
-    $cnt = kill 1, $child1, $child2;
-    kill 9, @goners;
-
-If SIGNAL is zero, no signal is sent to the process, but C<kill>
-checks whether it's I<possible> to send a signal to it (that
-means, to be brief, that the process is owned by the same user, or we are
-the super-user).  This is useful to check that a child process is still
-alive (even if only as a zombie) and hasn't changed its UID.  See
-L<perlport> for notes on the portability of this construct.
-
-Unlike in the shell, if SIGNAL is negative, it kills process groups instead
-of processes. That means you usually want to use positive not negative signals.
-You may also use a signal name in quotes.
-
-The behavior of kill when a I<PROCESS> number is zero or negative depends on
-the operating system.  For example, on POSIX-conforming systems, zero will
-signal the current process group and -1 will signal all processes.
-
-See L<perlipc/"Signals"> for more details.
-
-On some platforms such as Windows where the fork() system call is not available.
-Perl can be built to emulate fork() at the interpreter level.
-This emulation has limitations related to kill that have to be considered,
-for code running on Windows and in code intended to be portable.
-
-See L<perlfork> for more details.
-
-Portability issues: L<perlport/kill>.
-
-=item last LABEL
-X<last> X<break>
-
-=item last
-
-The C<last> command is like the C<break> statement in C (as used in
-loops); it immediately exits the loop in question.  If the LABEL is
-omitted, the command refers to the innermost enclosing loop.  The
-C<continue> block, if any, is not executed:
-
-    LINE: while (<STDIN>) {
-        last LINE if /^$/;  # exit when done with header
-        #...
-    }
-
-C<last> cannot be used to exit a block that returns a value such as
-C<eval {}>, C<sub {}>, or C<do {}>, and should not be used to exit
-a grep() or map() operation.
-
-Note that a block by itself is semantically identical to a loop
-that executes once.  Thus C<last> can be used to effect an early
-exit out of such a block.
-
-See also L</continue> for an illustration of how C<last>, C<next>, and
-C<redo> work.
-
-=item lc EXPR
-X<lc> X<lowercase>
-
-=item lc
-
-Returns a lowercased version of EXPR.  This is the internal function
-implementing the C<\L> escape in double-quoted strings.
-
-If EXPR is omitted, uses C<$_>.
-
-What gets returned depends on several factors:
-
-=over
-
-=item If C<use bytes> is in effect:
-
-=over
-
-=item On EBCDIC platforms
-
-The results are what the C language system call C<tolower()> returns.
-
-=item On ASCII platforms
-
-The results follow ASCII semantics.  Only characters C<A-Z> change, to C<a-z>
-respectively.
-
-=back
-
-=item Otherwise, If EXPR has the UTF8 flag set
-
-Unicode semantics are used for the case change.
-
-=item Otherwise, if C<use locale> is in effect
-
-Respects current LC_CTYPE locale.  See L<perllocale>.
-
-=item Otherwise, if C<use feature 'unicode_strings'> is in effect:
-
-Unicode semantics are used for the case change.
-
-=item Otherwise:
-
-=over
-
-=item On EBCDIC platforms
-
-The results are what the C language system call C<tolower()> returns.
-
-=item On ASCII platforms
-
-ASCII semantics are used for the case change.  The lowercase of any character
-outside the ASCII range is the character itself.
-
-=back
-
-=back
-
-=item lcfirst EXPR
-X<lcfirst> X<lowercase>
-
-=item lcfirst
-
-Returns the value of EXPR with the first character lowercased.  This
-is the internal function implementing the C<\l> escape in
-double-quoted strings.
-
-If EXPR is omitted, uses C<$_>.
-
-This function behaves the same way under various pragmata, such as in a locale,
-as L</lc> does.
-
-=item length EXPR
-X<length> X<size>
-
-=item length
-
-Returns the length in I<characters> of the value of EXPR.  If EXPR is
-omitted, returns the length of C<$_>.  If EXPR is undefined, returns
-C<undef>.
-
-This function cannot be used on an entire array or hash to find out how
-many elements these have.  For that, use C<scalar @array> and C<scalar keys
-%hash>, respectively.
-
-Like all Perl character operations, length() normally deals in logical
-characters, not physical bytes.  For how many bytes a string encoded as
-UTF-8 would take up, use C<length(Encode::encode_utf8(EXPR))> (you'll have
-to C<use Encode> first).  See L<Encode> and L<perlunicode>.
-
-=item __LINE__
-X<__LINE__>
-
-A special token that compiles to the current line number.
-
-=item link OLDFILE,NEWFILE
-X<link>
-
-Creates a new filename linked to the old filename.  Returns true for
-success, false otherwise.
-
-Portability issues: L<perlport/link>.
-
-=item listen SOCKET,QUEUESIZE
-X<listen>
-
-Does the same thing that the listen(2) system call does.  Returns true if
-it succeeded, false otherwise.  See the example in
-L<perlipc/"Sockets: Client/Server Communication">.
-
-=item local EXPR
-X<local>
-
-You really probably want to be using C<my> instead, because C<local> isn't
-what most people think of as "local".  See
-L<perlsub/"Private Variables via my()"> for details.
-
-A local modifies the listed variables to be local to the enclosing
-block, file, or eval.  If more than one value is listed, the list must
-be placed in parentheses.  See L<perlsub/"Temporary Values via local()">
-for details, including issues with tied arrays and hashes.
-
-The C<delete local EXPR> construct can also be used to localize the deletion
-of array/hash elements to the current block.
-See L<perlsub/"Localized deletion of elements of composite types">.
-
-=item localtime EXPR
-X<localtime> X<ctime>
-
-=item localtime
-
-Converts a time as returned by the time function to a 9-element list
-with the time analyzed for the local time zone.  Typically used as
-follows:
-
-    #  0    1    2     3     4    5     6     7     8
-    ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
-                                                localtime(time);
-
-All list elements are numeric and come straight out of the C `struct
-tm'.  C<$sec>, C<$min>, and C<$hour> are the seconds, minutes, and hours
-of the specified time.
-
-C<$mday> is the day of the month and C<$mon> the month in
-the range C<0..11>, with 0 indicating January and 11 indicating December.
-This makes it easy to get a month name from a list:
-
-    my @abbr = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
-    print "$abbr[$mon] $mday";
-    # $mon=9, $mday=18 gives "Oct 18"
-
-C<$year> is the number of years since 1900, B<not> just the last two digits
-of the year.  That is, C<$year> is C<123> in year 2023.  The proper way
-to get a 4-digit year is simply:
-
-    $year += 1900;
-
-Otherwise you create non-Y2K-compliant programs--and you wouldn't want
-to do that, would you?
-
-To get the last two digits of the year (e.g., "01" in 2001) do:
-
-    $year = sprintf("%02d", $year % 100);
-
-C<$wday> is the day of the week, with 0 indicating Sunday and 3 indicating
-Wednesday.  C<$yday> is the day of the year, in the range C<0..364>
-(or C<0..365> in leap years.)
-
-C<$isdst> is true if the specified time occurs during Daylight Saving
-Time, false otherwise.
-
-If EXPR is omitted, C<localtime()> uses the current time (as returned
-by time(3)).
-
-In scalar context, C<localtime()> returns the ctime(3) value:
-
-    $now_string = localtime;  # e.g., "Thu Oct 13 04:54:34 1994"
-
-This scalar value is B<not> locale-dependent but is a Perl builtin. For GMT
-instead of local time use the L</gmtime> builtin. See also the
-C<Time::Local> module (for converting seconds, minutes, hours, and such back to
-the integer value returned by time()), and the L<POSIX> module's strftime(3)
-and mktime(3) functions.
-
-To get somewhat similar but locale-dependent date strings, set up your
-locale environment variables appropriately (please see L<perllocale>) and
-try for example:
-
-    use POSIX qw(strftime);
-    $now_string = strftime "%a %b %e %H:%M:%S %Y", localtime;
-    # or for GMT formatted appropriately for your locale:
-    $now_string = strftime "%a %b %e %H:%M:%S %Y", gmtime;
-
-Note that the C<%a> and C<%b>, the short forms of the day of the week
-and the month of the year, may not necessarily be three characters wide.
-
-The L<Time::gmtime> and L<Time::localtime> modules provide a convenient,
-by-name access mechanism to the gmtime() and localtime() functions,
-respectively.
-
-For a comprehensive date and time representation look at the
-L<DateTime> module on CPAN.
-
-Portability issues: L<perlport/localtime>.
-
-=item lock THING
-X<lock>
-
-This function places an advisory lock on a shared variable or referenced
-object contained in I<THING> until the lock goes out of scope.
-
-The value returned is the scalar itself, if the argument is a scalar, or a
-reference, if the argument is a hash, array or subroutine.
-
-lock() is a "weak keyword" : this means that if you've defined a function
-by this name (before any calls to it), that function will be called
-instead.  If you are not under C<use threads::shared> this does nothing.
-See L<threads::shared>.
-
-=item log EXPR
-X<log> X<logarithm> X<e> X<ln> X<base>
-
-=item log
-
-Returns the natural logarithm (base I<e>) of EXPR.  If EXPR is omitted,
-returns the log of C<$_>.  To get the
-log of another base, use basic algebra:
-The base-N log of a number is equal to the natural log of that number
-divided by the natural log of N.  For example:
-
-    sub log10 {
-        my $n = shift;
-        return log($n)/log(10);
-    }
-
-See also L</exp> for the inverse operation.
-
-=item lstat FILEHANDLE
-X<lstat>
-
-=item lstat EXPR
-
-=item lstat DIRHANDLE
-
-=item lstat
-
-Does the same thing as the C<stat> function (including setting the
-special C<_> filehandle) but stats a symbolic link instead of the file
-the symbolic link points to.  If symbolic links are unimplemented on
-your system, a normal C<stat> is done.  For much more detailed
-information, please see the documentation for C<stat>.
-
-If EXPR is omitted, stats C<$_>.
-
-Portability issues: L<perlport/lstat>.
-
-=item m//
-
-The match operator.  See L<perlop/"Regexp Quote-Like Operators">.
-
-=item map BLOCK LIST
-X<map>
-
-=item map EXPR,LIST
-
-Evaluates the BLOCK or EXPR for each element of LIST (locally setting
-C<$_> to each element) and returns the list value composed of the
-results of each such evaluation.  In scalar context, returns the
-total number of elements so generated.  Evaluates BLOCK or EXPR in
-list context, so each element of LIST may produce zero, one, or
-more elements in the returned value.
-
-    @chars = map(chr, @numbers);
-
-translates a list of numbers to the corresponding characters.
-
-    my @squares = map { $_ * $_ } @numbers;
-
-translates a list of numbers to their squared values.
-
-    my @squares = map { $_ > 5 ? ($_ * $_) : () } @numbers;
-
-shows that number of returned elements can differ from the number of
-input elements. To omit an element, return an empty list ().
-This could also be achieved by writing
-
-    my @squares = map { $_ * $_ } grep { $_ > 5 } @numbers;
-
-which makes the intention more clear.
-
-Map always returns a list, which can be
-assigned to a hash such that the elements
-become key/value pairs. See L<perldata> for more details.
-
-    %hash = map { get_a_key_for($_) => $_ } @array;
-
-is just a funny way to write
-
-    %hash = ();
-    foreach (@array) {
-        $hash{get_a_key_for($_)} = $_;
-    }
-
-Note that C<$_> is an alias to the list value, so it can be used to
-modify the elements of the LIST.  While this is useful and supported,
-it can cause bizarre results if the elements of LIST are not variables.
-Using a regular C<foreach> loop for this purpose would be clearer in
-most cases.  See also L</grep> for an array composed of those items of
-the original list for which the BLOCK or EXPR evaluates to true.
-
-If C<$_> is lexical in the scope where the C<map> appears (because it has
-been declared with C<my $_>), then, in addition to being locally aliased to
-the list elements, C<$_> keeps being lexical inside the block; that is, it
-can't be seen from the outside, avoiding any potential side-effects.
-
-C<{> starts both hash references and blocks, so C<map { ...> could be either
-the start of map BLOCK LIST or map EXPR, LIST. Because Perl doesn't look
-ahead for the closing C<}> it has to take a guess at which it's dealing with
-based on what it finds just after the C<{>. Usually it gets it right, but if it
-doesn't it won't realize something is wrong until it gets to the C<}> and
-encounters the missing (or unexpected) comma. The syntax error will be
-reported close to the C<}>, but you'll need to change something near the C<{>
-such as using a unary C<+> to give Perl some help:
-
-    %hash = map {  "\L$_" => 1  } @array  # perl guesses EXPR.  wrong
-    %hash = map { +"\L$_" => 1  } @array  # perl guesses BLOCK. right
-    %hash = map { ("\L$_" => 1) } @array  # this also works
-    %hash = map {  lc($_) => 1  } @array  # as does this.
-    %hash = map +( lc($_) => 1 ), @array  # this is EXPR and works!
-
-    %hash = map  ( lc($_), 1 ),   @array  # evaluates to (1, @array)
-
-or to force an anon hash constructor use C<+{>:
-
-   @hashes = map +{ lc($_) => 1 }, @array # EXPR, so needs comma at end
-
-to get a list of anonymous hashes each with only one entry apiece.
-
-=item mkdir FILENAME,MASK
-X<mkdir> X<md> X<directory, create>
-
-=item mkdir FILENAME
-
-=item mkdir
-
-Creates the directory specified by FILENAME, with permissions
-specified by MASK (as modified by C<umask>).  If it succeeds it
-returns true; otherwise it returns false and sets C<$!> (errno).
-MASK defaults to 0777 if omitted, and FILENAME defaults
-to C<$_> if omitted.
-
-In general, it is better to create directories with a permissive MASK
-and let the user modify that with their C<umask> than it is to supply
-a restrictive MASK and give the user no way to be more permissive.
-The exceptions to this rule are when the file or directory should be
-kept private (mail files, for instance).  The perlfunc(1) entry on
-C<umask> discusses the choice of MASK in more detail.
-
-Note that according to the POSIX 1003.1-1996 the FILENAME may have any
-number of trailing slashes.  Some operating and filesystems do not get
-this right, so Perl automatically removes all trailing slashes to keep
-everyone happy.
-
-To recursively create a directory structure, look at
-the C<mkpath> function of the L<File::Path> module.
-
-=item msgctl ID,CMD,ARG
-X<msgctl>
-
-Calls the System V IPC function msgctl(2).  You'll probably have to say
-
-    use IPC::SysV;
-
-first to get the correct constant definitions.  If CMD is C<IPC_STAT>,
-then ARG must be a variable that will hold the returned C<msqid_ds>
-structure.  Returns like C<ioctl>: the undefined value for error,
-C<"0 but true"> for zero, or the actual return value otherwise.  See also
-L<perlipc/"SysV IPC"> and the documentation for C<IPC::SysV> and
-C<IPC::Semaphore>.
-
-Portability issues: L<perlport/msgctl>.
-
-=item msgget KEY,FLAGS
-X<msgget>
-
-Calls the System V IPC function msgget(2).  Returns the message queue
-id, or C<undef> on error.  See also
-L<perlipc/"SysV IPC"> and the documentation for C<IPC::SysV> and
-C<IPC::Msg>.
-
-Portability issues: L<perlport/msgget>.
-
-=item msgrcv ID,VAR,SIZE,TYPE,FLAGS
-X<msgrcv>
-
-Calls the System V IPC function msgrcv to receive a message from
-message queue ID into variable VAR with a maximum message size of
-SIZE.  Note that when a message is received, the message type as a
-native long integer will be the first thing in VAR, followed by the
-actual message.  This packing may be opened with C<unpack("l! a*")>.
-Taints the variable.  Returns true if successful, false 
-on error.  See also L<perlipc/"SysV IPC"> and the documentation for
-C<IPC::SysV> and C<IPC::SysV::Msg>.
-
-Portability issues: L<perlport/msgrcv>.
-
-=item msgsnd ID,MSG,FLAGS
-X<msgsnd>
-
-Calls the System V IPC function msgsnd to send the message MSG to the
-message queue ID.  MSG must begin with the native long integer message
-type, be followed by the length of the actual message, and then finally
-the message itself.  This kind of packing can be achieved with
-C<pack("l! a*", $type, $message)>.  Returns true if successful,
-false on error.  See also the C<IPC::SysV>
-and C<IPC::SysV::Msg> documentation.
-
-Portability issues: L<perlport/msgsnd>.
-
-=item my EXPR
-X<my>
-
-=item my TYPE EXPR
-
-=item my EXPR : ATTRS
-
-=item my TYPE EXPR : ATTRS
-
-A C<my> declares the listed variables to be local (lexically) to the
-enclosing block, file, or C<eval>.  If more than one value is listed,
-the list must be placed in parentheses.
-
-The exact semantics and interface of TYPE and ATTRS are still
-evolving.  TYPE is currently bound to the use of the C<fields> pragma,
-and attributes are handled using the C<attributes> pragma, or starting
-from Perl 5.8.0 also via the C<Attribute::Handlers> module.  See
-L<perlsub/"Private Variables via my()"> for details, and L<fields>,
-L<attributes>, and L<Attribute::Handlers>.
-
-=item next LABEL
-X<next> X<continue>
-
-=item next
-
-The C<next> command is like the C<continue> statement in C; it starts
-the next iteration of the loop:
-
-    LINE: while (<STDIN>) {
-        next LINE if /^#/;  # discard comments
-        #...
-    }
-
-Note that if there were a C<continue> block on the above, it would get
-executed even on discarded lines.  If LABEL is omitted, the command
-refers to the innermost enclosing loop.
-
-C<next> cannot be used to exit a block which returns a value such as
-C<eval {}>, C<sub {}>, or C<do {}>, and should not be used to exit
-a grep() or map() operation.
-
-Note that a block by itself is semantically identical to a loop
-that executes once.  Thus C<next> will exit such a block early.
-
-See also L</continue> for an illustration of how C<last>, C<next>, and
-C<redo> work.
-
-=item no MODULE VERSION LIST
-X<no declarations>
-X<unimporting>
-
-=item no MODULE VERSION
-
-=item no MODULE LIST
-
-=item no MODULE
-
-=item no VERSION
-
-See the C<use> function, of which C<no> is the opposite.
-
-=item oct EXPR
-X<oct> X<octal> X<hex> X<hexadecimal> X<binary> X<bin>
-
-=item oct
-
-Interprets EXPR as an octal string and returns the corresponding
-value.  (If EXPR happens to start off with C<0x>, interprets it as a
-hex string.  If EXPR starts off with C<0b>, it is interpreted as a
-binary string.  Leading whitespace is ignored in all three cases.)
-The following will handle decimal, binary, octal, and hex in standard
-Perl notation:
-
-    $val = oct($val) if $val =~ /^0/;
-
-If EXPR is omitted, uses C<$_>.   To go the other way (produce a number
-in octal), use sprintf() or printf():
-
-    $dec_perms = (stat("filename"))[2] & 07777;
-    $oct_perm_str = sprintf "%o", $perms;
-
-The oct() function is commonly used when a string such as C<644> needs
-to be converted into a file mode, for example.  Although Perl 
-automatically converts strings into numbers as needed, this automatic
-conversion assumes base 10.
-
-Leading white space is ignored without warning, as too are any trailing 
-non-digits, such as a decimal point (C<oct> only handles non-negative
-integers, not negative integers or floating point).
-
-=item open FILEHANDLE,EXPR
-X<open> X<pipe> X<file, open> X<fopen>
-
-=item open FILEHANDLE,MODE,EXPR
-
-=item open FILEHANDLE,MODE,EXPR,LIST
-
-=item open FILEHANDLE,MODE,REFERENCE
-
-=item open FILEHANDLE
-
-Opens the file whose filename is given by EXPR, and associates it with
-FILEHANDLE.
-
-Simple examples to open a file for reading:
-
-    open(my $fh, "<", "input.txt") 
-	or die "cannot open < input.txt: $!";
-
-and for writing:
-
-    open(my $fh, ">", "output.txt") 
-	or die "cannot open > output.txt: $!";
-
-(The following is a comprehensive reference to open(): for a gentler
-introduction you may consider L<perlopentut>.)
-
-If FILEHANDLE is an undefined scalar variable (or array or hash element), a
-new filehandle is autovivified, meaning that the variable is assigned a
-reference to a newly allocated anonymous filehandle.  Otherwise if
-FILEHANDLE is an expression, its value is the real filehandle.  (This is
-considered a symbolic reference, so C<use strict "refs"> should I<not> be
-in effect.)
-
-If EXPR is omitted, the global (package) scalar variable of the same
-name as the FILEHANDLE contains the filename.  (Note that lexical 
-variables--those declared with C<my> or C<state>--will not work for this
-purpose; so if you're using C<my> or C<state>, specify EXPR in your
-call to open.)
-
-If three (or more) arguments are specified, the open mode (including
-optional encoding) in the second argument are distinct from the filename in
-the third.  If MODE is C<< < >> or nothing, the file is opened for input.
-If MODE is C<< > >>, the file is opened for output, with existing files
-first being truncated ("clobbered") and nonexisting files newly created.
-If MODE is C<<< >> >>>, the file is opened for appending, again being
-created if necessary.
-
-You can put a C<+> in front of the C<< > >> or C<< < >> to
-indicate that you want both read and write access to the file; thus
-C<< +< >> is almost always preferred for read/write updates--the 
-C<< +> >> mode would clobber the file first.  You cant usually use
-either read-write mode for updating textfiles, since they have
-variable-length records.  See the B<-i> switch in L<perlrun> for a
-better approach.  The file is created with permissions of C<0666>
-modified by the process's C<umask> value.
-
-These various prefixes correspond to the fopen(3) modes of C<r>,
-C<r+>, C<w>, C<w+>, C<a>, and C<a+>.
-
-In the one- and two-argument forms of the call, the mode and filename
-should be concatenated (in that order), preferably separated by white
-space.  You can--but shouldn't--omit the mode in these forms when that mode
-is C<< < >>.  It is always safe to use the two-argument form of C<open> if
-the filename argument is a known literal.
-
-For three or more arguments if MODE is C<|->, the filename is
-interpreted as a command to which output is to be piped, and if MODE
-is C<-|>, the filename is interpreted as a command that pipes
-output to us.  In the two-argument (and one-argument) form, one should
-replace dash (C<->) with the command.
-See L<perlipc/"Using open() for IPC"> for more examples of this.
-(You are not allowed to C<open> to a command that pipes both in I<and>
-out, but see L<IPC::Open2>, L<IPC::Open3>, and
-L<perlipc/"Bidirectional Communication with Another Process"> for
-alternatives.)
-
-In the form of pipe opens taking three or more arguments, if LIST is specified
-(extra arguments after the command name) then LIST becomes arguments
-to the command invoked if the platform supports it.  The meaning of
-C<open> with more than three arguments for non-pipe modes is not yet
-defined, but experimental "layers" may give extra LIST arguments
-meaning.
-
-In the two-argument (and one-argument) form, opening C<< <- >> 
-or C<-> opens STDIN and opening C<< >- >> opens STDOUT.
-
-You may (and usually should) use the three-argument form of open to specify
-I/O layers (sometimes referred to as "disciplines") to apply to the handle
-that affect how the input and output are processed (see L<open> and
-L<PerlIO> for more details). For example:
-
-  open(my $fh, "<:encoding(UTF-8)", "filename")
-    || die "can't open UTF-8 encoded filename: $!";
-
-opens the UTF8-encoded file containing Unicode characters;
-see L<perluniintro>. Note that if layers are specified in the
-three-argument form, then default layers stored in ${^OPEN} (see L<perlvar>;
-usually set by the B<open> pragma or the switch B<-CioD>) are ignored.
-Those layers will also be ignored if you specifying a colon with no name
-following it.  In that case the default layer for the operating system
-(:raw on Unix, :crlf on Windows) is used.
-
-Open returns nonzero on success, the undefined value otherwise.  If
-the C<open> involved a pipe, the return value happens to be the pid of
-the subprocess.
-
-If you're running Perl on a system that distinguishes between text
-files and binary files, then you should check out L</binmode> for tips
-for dealing with this.  The key distinction between systems that need
-C<binmode> and those that don't is their text file formats.  Systems
-like Unix, Mac OS, and Plan 9, that end lines with a single
-character and encode that character in C as C<"\n"> do not
-need C<binmode>.  The rest need it.
-
-When opening a file, it's seldom a good idea to continue 
-if the request failed, so C<open> is frequently used with
-C<die>.  Even if C<die> won't do what you want (say, in a CGI script,
-where you want to format a suitable error message (but there are
-modules that can help with that problem)) always check
-the return value from opening a file.  
-
-As a special case the three-argument form with a read/write mode and the third
-argument being C<undef>:
-
-    open(my $tmp, "+>", undef) or die ...
-
-opens a filehandle to an anonymous temporary file.  Also using C<< +< >>
-works for symmetry, but you really should consider writing something
-to the temporary file first.  You will need to seek() to do the
-reading.
-
-Since v5.8.0, Perl has built using PerlIO by default.  Unless you've
-changed this (such as building Perl with C<Configure -Uuseperlio>), you can
-open filehandles directly to Perl scalars via:
-
-    open($fh, ">", \$variable) || ..
-
-To (re)open C<STDOUT> or C<STDERR> as an in-memory file, close it first:
-
-    close STDOUT;
-    open(STDOUT, ">", \$variable)
-	or die "Can't open STDOUT: $!";
-
-General examples:
-
-    $ARTICLE = 100;
-    open(ARTICLE) or die "Can't find article $ARTICLE: $!\n";
-    while (<ARTICLE>) {...
-
-    open(LOG, ">>/usr/spool/news/twitlog");  # (log is reserved)
-    # if the open fails, output is discarded
-
-    open(my $dbase, "+<", "dbase.mine")      # open for update
-        or die "Can't open 'dbase.mine' for update: $!";
-
-    open(my $dbase, "+<dbase.mine")          # ditto
-        or die "Can't open 'dbase.mine' for update: $!";
-
-    open(ARTICLE, "-|", "caesar <$article")  # decrypt article
-        or die "Can't start caesar: $!";
-
-    open(ARTICLE, "caesar <$article |")      # ditto
-        or die "Can't start caesar: $!";
-
-    open(EXTRACT, "|sort >Tmp$$")            # $$ is our process id
-        or die "Can't start sort: $!";
-
-    # in-memory files
-    open(MEMORY, ">", \$var)
-        or die "Can't open memory file: $!";
-    print MEMORY "foo!\n";                   # output will appear in $var
-
-    # process argument list of files along with any includes
-
-    foreach $file (@ARGV) {
-        process($file, "fh00");
-    }
-
-    sub process {
-        my($filename, $input) = @_;
-        $input++;    # this is a string increment
-        unless (open($input, "<", $filename)) {
-            print STDERR "Can't open $filename: $!\n";
-            return;
-        }
-
-        local $_;
-        while (<$input>) {    # note use of indirection
-            if (/^#include "(.*)"/) {
-                process($1, $input);
-                next;
-            }
-            #...          # whatever
-        }
-    }
-
-See L<perliol> for detailed info on PerlIO.
-
-You may also, in the Bourne shell tradition, specify an EXPR beginning
-with C<< >& >>, in which case the rest of the string is interpreted
-as the name of a filehandle (or file descriptor, if numeric) to be
-duped (as C<dup(2)>) and opened.  You may use C<&> after C<< > >>,
-C<<< >> >>>, C<< < >>, C<< +> >>, C<<< +>> >>>, and C<< +< >>.
-The mode you specify should match the mode of the original filehandle.
-(Duping a filehandle does not take into account any existing contents
-of IO buffers.) If you use the three-argument form, then you can pass either a
-number, the name of a filehandle, or the normal "reference to a glob".
-
-Here is a script that saves, redirects, and restores C<STDOUT> and
-C<STDERR> using various methods:
-
-    #!/usr/bin/perl
-    open(my $oldout, ">&STDOUT")     or die "Can't dup STDOUT: $!";
-    open(OLDERR,     ">&", \*STDERR) or die "Can't dup STDERR: $!";
-
-    open(STDOUT, '>', "foo.out") or die "Can't redirect STDOUT: $!";
-    open(STDERR, ">&STDOUT")     or die "Can't dup STDOUT: $!";
-
-    select STDERR; $| = 1;  # make unbuffered
-    select STDOUT; $| = 1;  # make unbuffered
-
-    print STDOUT "stdout 1\n";  # this works for
-    print STDERR "stderr 1\n";  # subprocesses too
-
-    open(STDOUT, ">&", $oldout) or die "Can't dup \$oldout: $!";
-    open(STDERR, ">&OLDERR")    or die "Can't dup OLDERR: $!";
-
-    print STDOUT "stdout 2\n";
-    print STDERR "stderr 2\n";
-
-If you specify C<< '<&=X' >>, where C<X> is a file descriptor number
-or a filehandle, then Perl will do an equivalent of C's C<fdopen> of
-that file descriptor (and not call C<dup(2)>); this is more
-parsimonious of file descriptors.  For example:
-
-    # open for input, reusing the fileno of $fd
-    open(FILEHANDLE, "<&=$fd")
-
-or
-
-    open(FILEHANDLE, "<&=", $fd)
-
-or
-
-    # open for append, using the fileno of OLDFH
-    open(FH, ">>&=", OLDFH)
-
-or
-
-    open(FH, ">>&=OLDFH")
-
-Being parsimonious on filehandles is also useful (besides being
-parsimonious) for example when something is dependent on file
-descriptors, like for example locking using flock().  If you do just
-C<< open(A, ">>&B") >>, the filehandle A will not have the same file
-descriptor as B, and therefore flock(A) will not flock(B) nor vice
-versa.  But with C<< open(A, ">>&=B") >>, the filehandles will share
-the same underlying system file descriptor.
-
-Note that under Perls older than 5.8.0, Perl uses the standard C library's'
-fdopen() to implement the C<=> functionality.  On many Unix systems,
-fdopen() fails when file descriptors exceed a certain value, typically 255.
-For Perls 5.8.0 and later, PerlIO is (most often) the default.
-
-You can see whether your Perl was built with PerlIO by running C<perl -V>
-and looking for the C<useperlio=> line.  If C<useperlio> is C<define>, you
-have PerlIO; otherwise you don't.
-
-If you open a pipe on the command C<-> (that is, specify either C<|-> or C<-|>
-with the one- or two-argument forms of C<open>), 
-an implicit C<fork> is done, so C<open> returns twice: in the parent
-process it returns the pid
-of the child process, and in the child process it returns (a defined) C<0>.
-Use C<defined($pid)> or C<//> to determine whether the open was successful.
-
-For example, use either
-
-    $child_pid = open(FROM_KID, "-|") 	// die "can't fork: $!";
-
-or
-    $child_pid = open(TO_KID,   "|-") 	// die "can't fork: $!";
-
-followed by 
-
-    if ($child_pid) {
-	# am the parent:
-	# either write TO_KID or else read FROM_KID
-	...
-	wait $child_pid;
-    } else {
-	# am the child; use STDIN/STDOUT normally
-	...
-	exit;
-    } 
-
-The filehandle behaves normally for the parent, but I/O to that
-filehandle is piped from/to the STDOUT/STDIN of the child process.
-In the child process, the filehandle isn't opened--I/O happens from/to
-the new STDOUT/STDIN.  Typically this is used like the normal
-piped open when you want to exercise more control over just how the
-pipe command gets executed, such as when running setuid and
-you don't want to have to scan shell commands for metacharacters.
-
-The following blocks are more or less equivalent:
-
-    open(FOO, "|tr '[a-z]' '[A-Z]'");
-    open(FOO, "|-", "tr '[a-z]' '[A-Z]'");
-    open(FOO, "|-") || exec 'tr', '[a-z]', '[A-Z]';
-    open(FOO, "|-", "tr", '[a-z]', '[A-Z]');
-
-    open(FOO, "cat -n '$file'|");
-    open(FOO, "-|", "cat -n '$file'");
-    open(FOO, "-|") || exec "cat", "-n", $file;
-    open(FOO, "-|", "cat", "-n", $file);
-
-The last two examples in each block show the pipe as "list form", which is
-not yet supported on all platforms.  A good rule of thumb is that if
-your platform has a real C<fork()> (in other words, if your platform is
-Unix, including Linux and MacOS X), you can use the list form.  You would 
-want to use the list form of the pipe so you can pass literal arguments
-to the command without risk of the shell interpreting any shell metacharacters
-in them.  However, this also bars you from opening pipes to commands
-that intentionally contain shell metacharacters, such as:
-
-    open(FOO, "|cat -n | expand -4 | lpr")
-	// die "Can't open pipeline to lpr: $!";
-
-See L<perlipc/"Safe Pipe Opens"> for more examples of this.
-
-Beginning with v5.6.0, Perl will attempt to flush all files opened for
-output before any operation that may do a fork, but this may not be
-supported on some platforms (see L<perlport>).  To be safe, you may need
-to set C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method
-of C<IO::Handle> on any open handles.
-
-On systems that support a close-on-exec flag on files, the flag will
-be set for the newly opened file descriptor as determined by the value
-of C<$^F>.  See L<perlvar/$^F>.
-
-Closing any piped filehandle causes the parent process to wait for the
-child to finish, then returns the status value in C<$?> and
-C<${^CHILD_ERROR_NATIVE}>.
-
-The filename passed to the one- and two-argument forms of open() will
-have leading and trailing whitespace deleted and normal
-redirection characters honored.  This property, known as "magic open",
-can often be used to good effect.  A user could specify a filename of
-F<"rsh cat file |">, or you could change certain filenames as needed:
-
-    $filename =~ s/(.*\.gz)\s*$/gzip -dc < $1|/;
-    open(FH, $filename) or die "Can't open $filename: $!";
-
-Use the three-argument form to open a file with arbitrary weird characters in it,
-
-    open(FOO, "<", $file)
-	|| die "can't open < $file: $!";
-
-otherwise it's necessary to protect any leading and trailing whitespace:
-
-    $file =~ s#^(\s)#./$1#;
-    open(FOO, "< $file\0")
-	|| die "open failed: $!";
-
-(this may not work on some bizarre filesystems).  One should
-conscientiously choose between the I<magic> and I<three-argument> form
-of open():
-
-    open(IN, $ARGV[0]) || die "can't open $ARGV[0]: $!";
-
-will allow the user to specify an argument of the form C<"rsh cat file |">,
-but will not work on a filename that happens to have a trailing space, while
-
-    open(IN, "<", $ARGV[0])
-	|| die "can't open < $ARGV[0]: $!";
-
-will have exactly the opposite restrictions.
-
-If you want a "real" C C<open> (see L<open(2)> on your system), then you
-should use the C<sysopen> function, which involves no such magic (but may
-use subtly different filemodes than Perl open(), which is mapped to C
-fopen()).  This is another way to protect your filenames from
-interpretation.  For example:
-
-    use IO::Handle;
-    sysopen(HANDLE, $path, O_RDWR|O_CREAT|O_EXCL)
-        or die "sysopen $path: $!";
-    $oldfh = select(HANDLE); $| = 1; select($oldfh);
-    print HANDLE "stuff $$\n";
-    seek(HANDLE, 0, 0);
-    print "File contains: ", <HANDLE>;
-
-Using the constructor from the C<IO::Handle> package (or one of its
-subclasses, such as C<IO::File> or C<IO::Socket>), you can generate anonymous
-filehandles that have the scope of the variables used to hold them, then
-automatically (but silently) close once their reference counts become
-zero, typically at scope exit:
-
-    use IO::File;
-    #...
-    sub read_myfile_munged {
-        my $ALL = shift;
-	# or just leave it undef to autoviv
-        my $handle = IO::File->new;
-        open($handle, "<", "myfile") or die "myfile: $!";
-        $first = <$handle>
-            or return ();     # Automatically closed here.
-        mung($first) or die "mung failed";  # Or here.
-        return (first, <$handle>) if $ALL;  # Or here.
-        return $first;                      # Or here.
-    }
-
-B<WARNING:> The previous example has a bug because the automatic
-close that happens when the refcount on C<handle> does not
-properly detect and report failures.  I<Always> close the handle
-yourself and inspect the return value.
-
-    close($handle) 
-	|| warn "close failed: $!";
-
-See L</seek> for some details about mixing reading and writing.
-
-Portability issues: L<perlport/open>.
-
-=item opendir DIRHANDLE,EXPR
-X<opendir>
-
-Opens a directory named EXPR for processing by C<readdir>, C<telldir>,
-C<seekdir>, C<rewinddir>, and C<closedir>.  Returns true if successful.
-DIRHANDLE may be an expression whose value can be used as an indirect
-dirhandle, usually the real dirhandle name.  If DIRHANDLE is an undefined
-scalar variable (or array or hash element), the variable is assigned a
-reference to a new anonymous dirhandle; that is, it's autovivified.
-DIRHANDLEs have their own namespace separate from FILEHANDLEs.
-
-See the example at C<readdir>.
-
-=item ord EXPR
-X<ord> X<encoding>
-
-=item ord
-
-Returns the numeric value of the first character of EXPR.
-If EXPR is an empty string, returns 0.  If EXPR is omitted, uses C<$_>.
-(Note I<character>, not byte.)
-
-For the reverse, see L</chr>.
-See L<perlunicode> for more about Unicode.
-
-=item our EXPR
-X<our> X<global>
-
-=item our TYPE EXPR
-
-=item our EXPR : ATTRS
-
-=item our TYPE EXPR : ATTRS
-
-C<our> associates a simple name with a package variable in the current
-package for use within the current scope.  When C<use strict 'vars'> is in
-effect, C<our> lets you use declared global variables without qualifying
-them with package names, within the lexical scope of the C<our> declaration.
-In this way C<our> differs from C<use vars>, which is package-scoped.
-
-Unlike C<my> or C<state>, which allocates storage for a variable and
-associates a simple name with that storage for use within the current
-scope, C<our> associates a simple name with a package (read: global)
-variable in the current package, for use within the current lexical scope.
-In other words, C<our> has the same scoping rules as C<my> or C<state>, but
-does not necessarily create a variable.
-
-If more than one value is listed, the list must be placed
-in parentheses.
-
-    our $foo;
-    our($bar, $baz);
-
-An C<our> declaration declares a global variable that will be visible
-across its entire lexical scope, even across package boundaries.  The
-package in which the variable is entered is determined at the point
-of the declaration, not at the point of use.  This means the following
-behavior holds:
-
-    package Foo;
-    our $bar;      # declares $Foo::bar for rest of lexical scope
-    $bar = 20;
-
-    package Bar;
-    print $bar;    # prints 20, as it refers to $Foo::bar
-
-Multiple C<our> declarations with the same name in the same lexical
-scope are allowed if they are in different packages.  If they happen
-to be in the same package, Perl will emit warnings if you have asked
-for them, just like multiple C<my> declarations.  Unlike a second
-C<my> declaration, which will bind the name to a fresh variable, a
-second C<our> declaration in the same package, in the same scope, is
-merely redundant.
-
-    use warnings;
-    package Foo;
-    our $bar;      # declares $Foo::bar for rest of lexical scope
-    $bar = 20;
-
-    package Bar;
-    our $bar = 30; # declares $Bar::bar for rest of lexical scope
-    print $bar;    # prints 30
-
-    our $bar;      # emits warning but has no other effect
-    print $bar;    # still prints 30
-
-An C<our> declaration may also have a list of attributes associated
-with it.
-
-The exact semantics and interface of TYPE and ATTRS are still
-evolving.  TYPE is currently bound to the use of C<fields> pragma,
-and attributes are handled using the C<attributes> pragma, or starting
-from Perl 5.8.0 also via the C<Attribute::Handlers> module.  See
-L<perlsub/"Private Variables via my()"> for details, and L<fields>,
-L<attributes>, and L<Attribute::Handlers>.
-
-=item pack TEMPLATE,LIST
-X<pack>
-
-Takes a LIST of values and converts it into a string using the rules
-given by the TEMPLATE.  The resulting string is the concatenation of
-the converted values.  Typically, each converted value looks
-like its machine-level representation.  For example, on 32-bit machines
-an integer may be represented by a sequence of 4 bytes, which  will in
-Perl be presented as a string that's 4 characters long. 
-
-See L<perlpacktut> for an introduction to this function.
-
-The TEMPLATE is a sequence of characters that give the order and type
-of values, as follows:
-
-    a  A string with arbitrary binary data, will be null padded.
-    A  A text (ASCII) string, will be space padded.
-    Z  A null-terminated (ASCIZ) string, will be null padded.
-
-    b  A bit string (ascending bit order inside each byte,
-       like vec()).
-    B  A bit string (descending bit order inside each byte).
-    h  A hex string (low nybble first).
-    H  A hex string (high nybble first).
-
-    c  A signed char (8-bit) value.
-    C  An unsigned char (octet) value.
-    W  An unsigned char value (can be greater than 255).
-
-    s  A signed short (16-bit) value.
-    S  An unsigned short value.
-
-    l  A signed long (32-bit) value.
-    L  An unsigned long value.
-
-    q  A signed quad (64-bit) value.
-    Q  An unsigned quad value.
-         (Quads are available only if your system supports 64-bit
-          integer values _and_ if Perl has been compiled to support
-          those.  Raises an exception otherwise.)
-
-    i  A signed integer value.
-    I  A unsigned integer value.
-         (This 'integer' is _at_least_ 32 bits wide.  Its exact
-          size depends on what a local C compiler calls 'int'.)
-
-    n  An unsigned short (16-bit) in "network" (big-endian) order.
-    N  An unsigned long (32-bit) in "network" (big-endian) order.
-    v  An unsigned short (16-bit) in "VAX" (little-endian) order.
-    V  An unsigned long (32-bit) in "VAX" (little-endian) order.
-
-    j  A Perl internal signed integer value (IV).
-    J  A Perl internal unsigned integer value (UV).
-
-    f  A single-precision float in native format.
-    d  A double-precision float in native format.
-
-    F  A Perl internal floating-point value (NV) in native format
-    D  A float of long-double precision in native format.
-         (Long doubles are available only if your system supports
-          long double values _and_ if Perl has been compiled to
-          support those.  Raises an exception otherwise.)
-
-    p  A pointer to a null-terminated string.
-    P  A pointer to a structure (fixed-length string).
-
-    u  A uuencoded string.
-    U  A Unicode character number.  Encodes to a character in char-
-       acter mode and UTF-8 (or UTF-EBCDIC in EBCDIC platforms) in
-       byte mode.
-
-    w  A BER compressed integer (not an ASN.1 BER, see perlpacktut
-       for details).  Its bytes represent an unsigned integer in
-       base 128, most significant digit first, with as few digits
-       as possible.  Bit eight (the high bit) is set on each byte
-       except the last.
-
-    x  A null byte (a.k.a ASCII NUL, "\000", chr(0))
-    X  Back up a byte.
-    @  Null-fill or truncate to absolute position, counted from the
-       start of the innermost ()-group.
-    .  Null-fill or truncate to absolute position specified by
-       the value.
-    (  Start of a ()-group.
-
-One or more modifiers below may optionally follow certain letters in the
-TEMPLATE (the second column lists letters for which the modifier is valid):
-
-    !   sSlLiI     Forces native (short, long, int) sizes instead
-                   of fixed (16-/32-bit) sizes.
-
-        xX         Make x and X act as alignment commands.
-
-        nNvV       Treat integers as signed instead of unsigned.
-
-        @.         Specify position as byte offset in the internal
-                   representation of the packed string. Efficient but
-                   dangerous.
-
-    >   sSiIlLqQ   Force big-endian byte-order on the type.
-        jJfFdDpP   (The "big end" touches the construct.)
-
-    <   sSiIlLqQ   Force little-endian byte-order on the type.
-        jJfFdDpP   (The "little end" touches the construct.)
-
-The C<< > >> and C<< < >> modifiers can also be used on C<()> groups 
-to force a particular byte-order on all components in that group, 
-including all its subgroups.
-
-The following rules apply:
-
-=over 
-
-=item *
-
-Each letter may optionally be followed by a number indicating the repeat
-count.  A numeric repeat count may optionally be enclosed in brackets, as
-in C<pack("C[80]", @arr)>.  The repeat count gobbles that many values from
-the LIST when used with all format types other than C<a>, C<A>, C<Z>, C<b>,
-C<B>, C<h>, C<H>, C<@>, C<.>, C<x>, C<X>, and C<P>, where it means
-something else, described below.  Supplying a C<*> for the repeat count
-instead of a number means to use however many items are left, except for:
-
-=over 
-
-=item * 
-
-C<@>, C<x>, and C<X>, where it is equivalent to C<0>.
-
-=item * 
-
-<.>, where it means relative to the start of the string.
-
-=item * 
-
-C<u>, where it is equivalent to 1 (or 45, which here is equivalent).
-
-=back 
-
-One can replace a numeric repeat count with a template letter enclosed in
-brackets to use the packed byte length of the bracketed template for the
-repeat count.
-
-For example, the template C<x[L]> skips as many bytes as in a packed long,
-and the template C<"$t X[$t] $t"> unpacks twice whatever $t (when
-variable-expanded) unpacks.  If the template in brackets contains alignment
-commands (such as C<x![d]>), its packed length is calculated as if the
-start of the template had the maximal possible alignment.
-
-When used with C<Z>, a C<*> as the repeat count is guaranteed to add a
-trailing null byte, so the resulting string is always one byte longer than
-the byte length of the item itself.
-
-When used with C<@>, the repeat count represents an offset from the start
-of the innermost C<()> group.
-
-When used with C<.>, the repeat count determines the starting position to
-calculate the value offset as follows:
-
-=over 
-
-=item *
-
-If the repeat count is C<0>, it's relative to the current position.
-
-=item *
-
-If the repeat count is C<*>, the offset is relative to the start of the
-packed string.
-
-=item *
-
-And if it's an integer I<n>, the offset is relative to the start of the
-I<n>th innermost C<( )> group, or to the start of the string if I<n> is
-bigger then the group level.
-
-=back
-
-The repeat count for C<u> is interpreted as the maximal number of bytes
-to encode per line of output, with 0, 1 and 2 replaced by 45. The repeat 
-count should not be more than 65.
-
-=item *
-
-The C<a>, C<A>, and C<Z> types gobble just one value, but pack it as a
-string of length count, padding with nulls or spaces as needed.  When
-unpacking, C<A> strips trailing whitespace and nulls, C<Z> strips everything
-after the first null, and C<a> returns data with no stripping at all.
-
-If the value to pack is too long, the result is truncated.  If it's too
-long and an explicit count is provided, C<Z> packs only C<$count-1> bytes,
-followed by a null byte.  Thus C<Z> always packs a trailing null, except
-when the count is 0.
-
-=item *
-
-Likewise, the C<b> and C<B> formats pack a string that's that many bits long.
-Each such format generates 1 bit of the result.  These are typically followed
-by a repeat count like C<B8> or C<B64>.
-
-Each result bit is based on the least-significant bit of the corresponding
-input character, i.e., on C<ord($char)%2>.  In particular, characters C<"0">
-and C<"1"> generate bits 0 and 1, as do characters C<"\000"> and C<"\001">.
-
-Starting from the beginning of the input string, each 8-tuple
-of characters is converted to 1 character of output.  With format C<b>,
-the first character of the 8-tuple determines the least-significant bit of a
-character; with format C<B>, it determines the most-significant bit of
-a character.
-
-If the length of the input string is not evenly divisible by 8, the
-remainder is packed as if the input string were padded by null characters
-at the end.  Similarly during unpacking, "extra" bits are ignored.
-
-If the input string is longer than needed, remaining characters are ignored.
-
-A C<*> for the repeat count uses all characters of the input field.  
-On unpacking, bits are converted to a string of C<0>s and C<1>s.
-
-=item *
-
-The C<h> and C<H> formats pack a string that many nybbles (4-bit groups,
-representable as hexadecimal digits, C<"0".."9"> C<"a".."f">) long.
-
-For each such format, pack() generates 4 bits of result.
-With non-alphabetical characters, the result is based on the 4 least-significant
-bits of the input character, i.e., on C<ord($char)%16>.  In particular,
-characters C<"0"> and C<"1"> generate nybbles 0 and 1, as do bytes
-C<"\000"> and C<"\001">.  For characters C<"a".."f"> and C<"A".."F">, the result
-is compatible with the usual hexadecimal digits, so that C<"a"> and
-C<"A"> both generate the nybble C<0xA==10>.  Use only these specific hex 
-characters with this format.
-
-Starting from the beginning of the template to pack(), each pair
-of characters is converted to 1 character of output.  With format C<h>, the
-first character of the pair determines the least-significant nybble of the
-output character; with format C<H>, it determines the most-significant
-nybble.
-
-If the length of the input string is not even, it behaves as if padded by
-a null character at the end.  Similarly, "extra" nybbles are ignored during
-unpacking.
-
-If the input string is longer than needed, extra characters are ignored.
-
-A C<*> for the repeat count uses all characters of the input field.  For
-unpack(), nybbles are converted to a string of hexadecimal digits.
-
-=item *
-
-The C<p> format packs a pointer to a null-terminated string.  You are
-responsible for ensuring that the string is not a temporary value, as that
-could potentially get deallocated before you got around to using the packed
-result.  The C<P> format packs a pointer to a structure of the size indicated
-by the length.  A null pointer is created if the corresponding value for
-C<p> or C<P> is C<undef>; similarly with unpack(), where a null pointer
-unpacks into C<undef>.
-
-If your system has a strange pointer size--meaning a pointer is neither as
-big as an int nor as big as a long--it may not be possible to pack or
-unpack pointers in big- or little-endian byte order.  Attempting to do
-so raises an exception.
-
-=item *
-
-The C</> template character allows packing and unpacking of a sequence of
-items where the packed structure contains a packed item count followed by
-the packed items themselves.  This is useful when the structure you're
-unpacking has encoded the sizes or repeat counts for some of its fields
-within the structure itself as separate fields.
-
-For C<pack>, you write I<length-item>C</>I<sequence-item>, and the
-I<length-item> describes how the length value is packed. Formats likely
-to be of most use are integer-packing ones like C<n> for Java strings,
-C<w> for ASN.1 or SNMP, and C<N> for Sun XDR.
-
-For C<pack>, I<sequence-item> may have a repeat count, in which case
-the minimum of that and the number of available items is used as the argument
-for I<length-item>. If it has no repeat count or uses a '*', the number
-of available items is used.
-
-For C<unpack>, an internal stack of integer arguments unpacked so far is
-used. You write C</>I<sequence-item> and the repeat count is obtained by
-popping off the last element from the stack. The I<sequence-item> must not
-have a repeat count.
-
-If I<sequence-item> refers to a string type (C<"A">, C<"a">, or C<"Z">),
-the I<length-item> is the string length, not the number of strings.  With
-an explicit repeat count for pack, the packed string is adjusted to that
-length.  For example:
-
- This code:                              gives this result:
- 
-  unpack("W/a", "\004Gurusamy")          ("Guru")
-  unpack("a3/A A*", "007 Bond  J ")      (" Bond", "J")
-  unpack("a3 x2 /A A*", "007: Bond, J.") ("Bond, J", ".")
-
-  pack("n/a* w/a","hello,","world")     "\000\006hello,\005world"
-  pack("a/W2", ord("a") .. ord("z"))    "2ab"
-
-The I<length-item> is not returned explicitly from C<unpack>.
-
-Supplying a count to the I<length-item> format letter is only useful with
-C<A>, C<a>, or C<Z>.  Packing with a I<length-item> of C<a> or C<Z> may
-introduce C<"\000"> characters, which Perl does not regard as legal in
-numeric strings.
-
-=item *
-
-The integer types C<s>, C<S>, C<l>, and C<L> may be
-followed by a C<!> modifier to specify native shorts or
-longs.  As shown in the example above, a bare C<l> means
-exactly 32 bits, although the native C<long> as seen by the local C compiler
-may be larger.  This is mainly an issue on 64-bit platforms.  You can
-see whether using C<!> makes any difference this way:
-
-    printf "format s is %d, s! is %d\n", 
-	length pack("s"), length pack("s!");
-
-    printf "format l is %d, l! is %d\n", 
-	length pack("l"), length pack("l!");
-
-
-C<i!> and C<I!> are also allowed, but only for completeness' sake:
-they are identical to C<i> and C<I>.
-
-The actual sizes (in bytes) of native shorts, ints, longs, and long
-longs on the platform where Perl was built are also available from
-the command line:
-
-    $ perl -V:{short,int,long{,long}}size
-    shortsize='2';
-    intsize='4';
-    longsize='4';
-    longlongsize='8';
-
-or programmatically via the C<Config> module:
-
-       use Config;
-       print $Config{shortsize},    "\n";
-       print $Config{intsize},      "\n";
-       print $Config{longsize},     "\n";
-       print $Config{longlongsize}, "\n";
-
-C<$Config{longlongsize}> is undefined on systems without 
-long long support.
-
-=item *
-
-The integer formats C<s>, C<S>, C<i>, C<I>, C<l>, C<L>, C<j>, and C<J> are
-inherently non-portable between processors and operating systems because
-they obey native byteorder and endianness.  For example, a 4-byte integer
-0x12345678 (305419896 decimal) would be ordered natively (arranged in and
-handled by the CPU registers) into bytes as
-
-    0x12 0x34 0x56 0x78  # big-endian
-    0x78 0x56 0x34 0x12  # little-endian
-
-Basically, Intel and VAX CPUs are little-endian, while everybody else,
-including Motorola m68k/88k, PPC, Sparc, HP PA, Power, and Cray, are
-big-endian.  Alpha and MIPS can be either: Digital/Compaq uses (well, used) 
-them in little-endian mode, but SGI/Cray uses them in big-endian mode.
-
-The names I<big-endian> and I<little-endian> are comic references to the
-egg-eating habits of the little-endian Lilliputians and the big-endian
-Blefuscudians from the classic Jonathan Swift satire, I<Gulliver's Travels>.
-This entered computer lingo via the paper "On Holy Wars and a Plea for
-Peace" by Danny Cohen, USC/ISI IEN 137, April 1, 1980.
-
-Some systems may have even weirder byte orders such as
-
-   0x56 0x78 0x12 0x34
-   0x34 0x12 0x78 0x56
-
-You can determine your system endianness with this incantation:
-
-   printf("%#02x ", $_) for unpack("W*", pack L=>0x12345678); 
-
-The byteorder on the platform where Perl was built is also available
-via L<Config>:
-
-    use Config;
-    print "$Config{byteorder}\n";
-
-or from the command line:
-
-    $ perl -V:byteorder
-
-Byteorders C<"1234"> and C<"12345678"> are little-endian; C<"4321">
-and C<"87654321"> are big-endian.
-
-For portably packed integers, either use the formats C<n>, C<N>, C<v>, 
-and C<V> or else use the C<< > >> and C<< < >> modifiers described
-immediately below.  See also L<perlport>.
-
-=item *
-
-Starting with Perl 5.9.2, integer and floating-point formats, along with
-the C<p> and C<P> formats and C<()> groups, may all be followed by the 
-C<< > >> or C<< < >> endianness modifiers to respectively enforce big-
-or little-endian byte-order.  These modifiers are especially useful 
-given how C<n>, C<N>, C<v>, and C<V> don't cover signed integers, 
-64-bit integers, or floating-point values.
-
-Here are some concerns to keep in mind when using an endianness modifier:
-
-=over
-
-=item * 
-
-Exchanging signed integers between different platforms works only 
-when all platforms store them in the same format.  Most platforms store
-signed integers in two's-complement notation, so usually this is not an issue.
-
-=item * 
-
-The C<< > >> or C<< < >> modifiers can only be used on floating-point
-formats on big- or little-endian machines.  Otherwise, attempting to
-use them raises an exception.
-
-=item * 
-
-Forcing big- or little-endian byte-order on floating-point values for
-data exchange can work only if all platforms use the same
-binary representation such as IEEE floating-point.  Even if all
-platforms are using IEEE, there may still be subtle differences.  Being able
-to use C<< > >> or C<< < >> on floating-point values can be useful,
-but also dangerous if you don't know exactly what you're doing.
-It is not a general way to portably store floating-point values.
-
-=item * 
-
-When using C<< > >> or C<< < >> on a C<()> group, this affects
-all types inside the group that accept byte-order modifiers,
-including all subgroups.  It is silently ignored for all other
-types.  You are not allowed to override the byte-order within a group
-that already has a byte-order modifier suffix.
-
-=back
-
-=item *
-
-Real numbers (floats and doubles) are in native machine format only.
-Due to the multiplicity of floating-point formats and the lack of a
-standard "network" representation for them, no facility for interchange has been
-made.  This means that packed floating-point data written on one machine
-may not be readable on another, even if both use IEEE floating-point
-arithmetic (because the endianness of the memory representation is not part
-of the IEEE spec).  See also L<perlport>.
-
-If you know I<exactly> what you're doing, you can use the C<< > >> or C<< < >>
-modifiers to force big- or little-endian byte-order on floating-point values.
-
-Because Perl uses doubles (or long doubles, if configured) internally for
-all numeric calculation, converting from double into float and thence 
-to double again loses precision, so C<unpack("f", pack("f", $foo)>)
-will not in general equal $foo.
-
-=item *
-
-Pack and unpack can operate in two modes: character mode (C<C0> mode) where
-the packed string is processed per character, and UTF-8 mode (C<U0> mode)
-where the packed string is processed in its UTF-8-encoded Unicode form on
-a byte-by-byte basis. Character mode is the default unless the format string 
-starts with C<U>. You can always switch mode mid-format with an explicit 
-C<C0> or C<U0> in the format.  This mode remains in effect until the next 
-mode change, or until the end of the C<()> group it (directly) applies to.
-
-Using C<C0> to get Unicode characters while using C<U0> to get I<non>-Unicode 
-bytes is not necessarily obvious.   Probably only the first of these
-is what you want:
-
-    $ perl -CS -E 'say "\x{3B1}\x{3C9}"' | 
-      perl -CS -ne 'printf "%v04X\n", $_ for unpack("C0A*", $_)'
-    03B1.03C9
-    $ perl -CS -E 'say "\x{3B1}\x{3C9}"' | 
-      perl -CS -ne 'printf "%v02X\n", $_ for unpack("U0A*", $_)'
-    CE.B1.CF.89
-    $ perl -CS -E 'say "\x{3B1}\x{3C9}"' | 
-      perl -C0 -ne 'printf "%v02X\n", $_ for unpack("C0A*", $_)'
-    CE.B1.CF.89
-    $ perl -CS -E 'say "\x{3B1}\x{3C9}"' | 
-      perl -C0 -ne 'printf "%v02X\n", $_ for unpack("U0A*", $_)'
-    C3.8E.C2.B1.C3.8F.C2.89
-
-Those examples also illustrate that you should not try to use
-C<pack>/C<unpack> as a substitute for the L<Encode> module.
-
-=item *
-
-You must yourself do any alignment or padding by inserting, for example,
-enough C<"x">es while packing.  There is no way for pack() and unpack()
-to know where characters are going to or coming from, so they 
-handle their output and input as flat sequences of characters.
-
-=item *
-
-A C<()> group is a sub-TEMPLATE enclosed in parentheses.  A group may
-take a repeat count either as postfix, or for unpack(), also via the C</>
-template character.  Within each repetition of a group, positioning with
-C<@> starts over at 0. Therefore, the result of
-
-    pack("@1A((@2A)@3A)", qw[X Y Z])
-
-is the string C<"\0X\0\0YZ">.
-
-=item *
-
-C<x> and C<X> accept the C<!> modifier to act as alignment commands: they
-jump forward or back to the closest position aligned at a multiple of C<count>
-characters. For example, to pack() or unpack() a C structure like
-
-    struct {
-	char   c;    /* one signed, 8-bit character */
-	double d; 
-	char   cc[2];
-    }
-
-one may need to use the template C<c x![d] d c[2]>.  This assumes that
-doubles must be aligned to the size of double.
-
-For alignment commands, a C<count> of 0 is equivalent to a C<count> of 1;
-both are no-ops.
-
-=item *
-
-C<n>, C<N>, C<v> and C<V> accept the C<!> modifier to
-represent signed 16-/32-bit integers in big-/little-endian order.
-This is portable only when all platforms sharing packed data use the
-same binary representation for signed integers; for example, when all
-platforms use two's-complement representation.
-
-=item *
-
-Comments can be embedded in a TEMPLATE using C<#> through the end of line.
-White space can separate pack codes from each other, but modifiers and
-repeat counts must follow immediately.  Breaking complex templates into
-individual line-by-line components, suitably annotated, can do as much to
-improve legibility and maintainability of pack/unpack formats as C</x> can
-for complicated pattern matches.
-
-=item *
-
-If TEMPLATE requires more arguments than pack() is given, pack()
-assumes additional C<""> arguments.  If TEMPLATE requires fewer arguments
-than given, extra arguments are ignored.
-
-=back
-
-Examples:
-
-    $foo = pack("WWWW",65,66,67,68);
-    # foo eq "ABCD"
-    $foo = pack("W4",65,66,67,68);
-    # same thing
-    $foo = pack("W4",0x24b6,0x24b7,0x24b8,0x24b9);
-    # same thing with Unicode circled letters.
-    $foo = pack("U4",0x24b6,0x24b7,0x24b8,0x24b9);
-    # same thing with Unicode circled letters. You don't get the
-    # UTF-8 bytes because the U at the start of the format caused
-    # a switch to U0-mode, so the UTF-8 bytes get joined into
-    # characters
-    $foo = pack("C0U4",0x24b6,0x24b7,0x24b8,0x24b9);
-    # foo eq "\xe2\x92\xb6\xe2\x92\xb7\xe2\x92\xb8\xe2\x92\xb9"
-    # This is the UTF-8 encoding of the string in the
-    # previous example
-
-    $foo = pack("ccxxcc",65,66,67,68);
-    # foo eq "AB\0\0CD"
-
-    # NOTE: The examples above featuring "W" and "c" are true
-    # only on ASCII and ASCII-derived systems such as ISO Latin 1
-    # and UTF-8.  On EBCDIC systems, the first example would be
-    #      $foo = pack("WWWW",193,194,195,196);
-
-    $foo = pack("s2",1,2);
-    # "\001\000\002\000" on little-endian
-    # "\000\001\000\002" on big-endian
-
-    $foo = pack("a4","abcd","x","y","z");
-    # "abcd"
-
-    $foo = pack("aaaa","abcd","x","y","z");
-    # "axyz"
-
-    $foo = pack("a14","abcdefg");
-    # "abcdefg\0\0\0\0\0\0\0"
-
-    $foo = pack("i9pl", gmtime);
-    # a real struct tm (on my system anyway)
-
-    $utmp_template = "Z8 Z8 Z16 L";
-    $utmp = pack($utmp_template, @utmp1);
-    # a struct utmp (BSDish)
-
-    @utmp2 = unpack($utmp_template, $utmp);
-    # "@utmp1" eq "@utmp2"
-
-    sub bintodec {
-        unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
-    }
-
-    $foo = pack('sx2l', 12, 34);
-    # short 12, two zero bytes padding, long 34
-    $bar = pack('s@4l', 12, 34);
-    # short 12, zero fill to position 4, long 34
-    # $foo eq $bar
-    $baz = pack('s.l', 12, 4, 34);
-    # short 12, zero fill to position 4, long 34
-
-    $foo = pack('nN', 42, 4711);
-    # pack big-endian 16- and 32-bit unsigned integers
-    $foo = pack('S>L>', 42, 4711);
-    # exactly the same
-    $foo = pack('s<l<', -42, 4711);
-    # pack little-endian 16- and 32-bit signed integers
-    $foo = pack('(sl)<', -42, 4711);
-    # exactly the same
-
-The same template may generally also be used in unpack().
-
-=item package NAMESPACE
-
-=item package NAMESPACE VERSION
-X<package> X<module> X<namespace> X<version>
-
-=item package NAMESPACE BLOCK
-
-=item package NAMESPACE VERSION BLOCK
-X<package> X<module> X<namespace> X<version>
-
-Declares the BLOCK or the rest of the compilation unit as being in the
-given namespace.  The scope of the package declaration is either the
-supplied code BLOCK or, in the absence of a BLOCK, from the declaration
-itself through the end of current scope (the enclosing block, file, or
-C<eval>).  That is, the forms without a BLOCK are operative through the end
-of the current scope, just like the C<my>, C<state>, and C<our> operators.
-All unqualified dynamic identifiers in this scope will be in the given
-namespace, except where overridden by another C<package> declaration or
-when they're one of the special identifiers that qualify into C<main::>,
-like C<STDOUT>, C<ARGV>, C<ENV>, and the punctuation variables.
-
-A package statement affects dynamic variables only, including those
-you've used C<local> on, but I<not> lexical variables, which are created
-with C<my>, C<state>, or C<our>.  Typically it would be the first 
-declaration in a file included by C<require> or C<use>.  You can switch into a
-package in more than one place, since this only determines which default 
-symbol table the compiler uses for the rest of that block.  You can refer to
-identifiers in other packages than the current one by prefixing the identifier
-with the package name and a double colon, as in C<$SomePack::var>
-or C<ThatPack::INPUT_HANDLE>.  If package name is omitted, the C<main>
-package as assumed.  That is, C<$::sail> is equivalent to
-C<$main::sail> (as well as to C<$main'sail>, still seen in ancient
-code, mostly from Perl 4).
-
-If VERSION is provided, C<package> sets the C<$VERSION> variable in the given
-namespace to a L<version> object with the VERSION provided.  VERSION must be a
-"strict" style version number as defined by the L<version> module: a positive
-decimal number (integer or decimal-fraction) without exponentiation or else a
-dotted-decimal v-string with a leading 'v' character and at least three
-components.  You should set C<$VERSION> only once per package.
-
-See L<perlmod/"Packages"> for more information about packages, modules,
-and classes.  See L<perlsub> for other scoping issues.
-
-=item pipe READHANDLE,WRITEHANDLE
-X<pipe>
-
-Opens a pair of connected pipes like the corresponding system call.
-Note that if you set up a loop of piped processes, deadlock can occur
-unless you are very careful.  In addition, note that Perl's pipes use
-IO buffering, so you may need to set C<$|> to flush your WRITEHANDLE
-after each command, depending on the application.
-
-See L<IPC::Open2>, L<IPC::Open3>, and
-L<perlipc/"Bidirectional Communication with Another Process">
-for examples of such things.
-
-On systems that support a close-on-exec flag on files, that flag is set
-on all newly opened file descriptors whose C<fileno>s are I<higher> than 
-the current value of $^F (by default 2 for C<STDERR>).  See L<perlvar/$^F>.
-
-=item __PACKAGE__
-X<__PACKAGE__>
-
-A special token that returns the name of the package in which it occurs.
-
-=item pop ARRAY
-X<pop> X<stack>
-
-=item pop EXPR
-
-=item pop
-
-Pops and returns the last value of the array, shortening the array by
-one element.
-
-Returns the undefined value if the array is empty, although this may also
-happen at other times.  If ARRAY is omitted, pops the C<@ARGV> array in the
-main program, but the C<@_> array in subroutines, just like C<shift>.
-
-Starting with Perl 5.14, C<pop> can take a scalar EXPR, which must hold a
-reference to an unblessed array.  The argument will be dereferenced
-automatically.  This aspect of C<pop> is considered highly experimental.
-The exact behaviour may change in a future version of Perl.
-
-=item pos SCALAR
-X<pos> X<match, position>
-
-=item pos
-
-Returns the offset of where the last C<m//g> search left off for the
-variable in question (C<$_> is used when the variable is not
-specified). Note that 0 is a valid match offset. C<undef> indicates
-that the search position is reset (usually due to match failure, but
-can also be because no match has yet been run on the scalar).
-
-C<pos> directly accesses the location used by the regexp engine to
-store the offset, so assigning to C<pos> will change that offset, and
-so will also influence the C<\G> zero-width assertion in regular
-expressions. Both of these effects take place for the next match, so
-you can't affect the position with C<pos> during the current match,
-such as in C<(?{pos() = 5})> or C<s//pos() = 5/e>.
-
-Setting C<pos> also resets the I<matched with zero-length> flag, described
-under L<perlre/"Repeated Patterns Matching a Zero-length Substring">.
-
-Because a failed C<m//gc> match doesn't reset the offset, the return
-from C<pos> won't change either in this case.  See L<perlre> and
-L<perlop>.
-
-=item print FILEHANDLE LIST
-X<print>
-
-=item print FILEHANDLE
-
-=item print LIST
-
-=item print
-
-Prints a string or a list of strings.  Returns true if successful.
-FILEHANDLE may be a scalar variable containing the name of or a reference
-to the filehandle, thus introducing one level of indirection.  (NOTE: If
-FILEHANDLE is a variable and the next token is a term, it may be
-misinterpreted as an operator unless you interpose a C<+> or put
-parentheses around the arguments.) If FILEHANDLE is omitted, prints to the
-last selected (see L</select>) output handle.  If LIST is omitted, prints
-C<$_> to the currently selected output handle.  To use FILEHANDLE alone to
-print the content of C<$_> to it, you must use a real filehandle like
-C<FH>, not an indirect one like C<$fh>.  To set the default output handle
-to something other than STDOUT, use the select operation.
-
-The current value of C<$,> (if any) is printed between each LIST item.  The
-current value of C<$\> (if any) is printed after the entire LIST has been
-printed.  Because print takes a LIST, anything in the LIST is evaluated in
-list context, including any subroutines whose return lists you pass to
-C<print>.  Be careful not to follow the print keyword with a left
-parenthesis unless you want the corresponding right parenthesis to
-terminate the arguments to the print; put parentheses around all arguments
-(or interpose a C<+>, but that doesn't look as good).
-
-If you're storing handles in an array or hash, or in general whenever
-you're using any expression more complex than a bareword handle or a plain,
-unsubscripted scalar variable to retrieve it, you will have to use a block
-returning the filehandle value instead, in which case the LIST may not be
-omitted:
-
-    print { $files[$i] } "stuff\n";
-    print { $OK ? STDOUT : STDERR } "stuff\n";
-
-Printing to a closed pipe or socket will generate a SIGPIPE signal.  See
-L<perlipc> for more on signal handling.
-
-=item printf FILEHANDLE FORMAT, LIST
-X<printf>
-
-=item printf FILEHANDLE
-
-=item printf FORMAT, LIST
-
-=item printf
-
-Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>, except that C<$\>
-(the output record separator) is not appended.  The first argument of the
-list will be interpreted as the C<printf> format. See
-L<sprintf|/sprintf FORMAT, LIST> for an
-explanation of the format argument.    If you omit the LIST, C<$_> is used;
-to use FILEHANDLE without a LIST, you must use a real filehandle like
-C<FH>, not an indirect one like C<$fh>.  If C<use locale> is in effect and
-POSIX::setlocale() has been called, the character used for the decimal
-separator in formatted floating-point numbers is affected by the LC_NUMERIC
-locale setting.  See L<perllocale> and L<POSIX>.
-
-Don't fall into the trap of using a C<printf> when a simple
-C<print> would do.  The C<print> is more efficient and less
-error prone.
-
-=item prototype FUNCTION
-X<prototype>
-
-Returns the prototype of a function as a string (or C<undef> if the
-function has no prototype).  FUNCTION is a reference to, or the name of,
-the function whose prototype you want to retrieve.
-
-If FUNCTION is a string starting with C<CORE::>, the rest is taken as a
-name for a Perl builtin.  If the builtin is not I<overridable> (such as
-C<qw//>) or if its arguments cannot be adequately expressed by a prototype
-(such as C<system>), prototype() returns C<undef>, because the builtin
-does not really behave like a Perl function.  Otherwise, the string
-describing the equivalent prototype is returned.
-
-=item push ARRAY,LIST
-X<push> X<stack>
-
-=item push EXPR,LIST
-
-Treats ARRAY as a stack by appending the values of LIST to the end of
-ARRAY.  The length of ARRAY increases by the length of LIST.  Has the same
-effect as
-
-    for $value (LIST) {
-        $ARRAY[++$#ARRAY] = $value;
-    }
-
-but is more efficient.  Returns the number of elements in the array following
-the completed C<push>.
-
-Starting with Perl 5.14, C<push> can take a scalar EXPR, which must hold a
-reference to an unblessed array.  The argument will be dereferenced
-automatically.  This aspect of C<push> is considered highly experimental.
-The exact behaviour may change in a future version of Perl.
-
-=item q/STRING/
-
-=item qq/STRING/
-
-=item qx/STRING/
-
-=item qw/STRING/
-
-Generalized quotes.  See L<perlop/"Quote-Like Operators">.
-
-=item qr/STRING/
-
-Regexp-like quote.  See L<perlop/"Regexp Quote-Like Operators">.
-
-=item quotemeta EXPR
-X<quotemeta> X<metacharacter>
-
-=item quotemeta
-
-Returns the value of EXPR with all non-"word"
-characters backslashed.  (That is, all characters not matching
-C</[A-Za-z_0-9]/> will be preceded by a backslash in the
-returned string, regardless of any locale settings.)
-This is the internal function implementing
-the C<\Q> escape in double-quoted strings.
-
-If EXPR is omitted, uses C<$_>.
-
-quotemeta (and C<\Q> ... C<\E>) are useful when interpolating strings into
-regular expressions, because by default an interpolated variable will be
-considered a mini-regular expression. For example:
-
-    my $sentence = 'The quick brown fox jumped over the lazy dog';
-    my $substring = 'quick.*?fox';
-    $sentence =~ s{$substring}{big bad wolf};
-
-Will cause C<$sentence> to become C<'The big bad wolf jumped over...'>.
-
-On the other hand:
-
-    my $sentence = 'The quick brown fox jumped over the lazy dog';
-    my $substring = 'quick.*?fox';
-    $sentence =~ s{\Q$substring\E}{big bad wolf};
-
-Or:
-
-    my $sentence = 'The quick brown fox jumped over the lazy dog';
-    my $substring = 'quick.*?fox';
-    my $quoted_substring = quotemeta($substring);
-    $sentence =~ s{$quoted_substring}{big bad wolf};
-
-Will both leave the sentence as is. Normally, when accepting literal string
-input from the user, quotemeta() or C<\Q> must be used.
-
-In Perl 5.14, all characters whose code points are above 127 are not
-quoted in UTF8-encoded strings, but all are quoted in UTF-8 strings.
-It is planned to change this behavior in 5.16, but the exact rules
-haven't been determined yet.
-
-=item rand EXPR
-X<rand> X<random>
-
-=item rand
-
-Returns a random fractional number greater than or equal to C<0> and less
-than the value of EXPR.  (EXPR should be positive.)  If EXPR is
-omitted, the value C<1> is used.  Currently EXPR with the value C<0> is
-also special-cased as C<1> (this was undocumented before Perl 5.8.0
-and is subject to change in future versions of Perl).  Automatically calls
-C<srand> unless C<srand> has already been called.  See also C<srand>.
-
-Apply C<int()> to the value returned by C<rand()> if you want random
-integers instead of random fractional numbers.  For example,
-
-    int(rand(10))
-
-returns a random integer between C<0> and C<9>, inclusive.
-
-(Note: If your rand function consistently returns numbers that are too
-large or too small, then your version of Perl was probably compiled
-with the wrong number of RANDBITS.)
-
-B<C<rand()> is not cryptographically secure.  You should not rely
-on it in security-sensitive situations.>  As of this writing, a
-number of third-party CPAN modules offer random number generators
-intended by their authors to be cryptographically secure,
-including: L<Data::Entropy>, L<Crypt::Random>, L<Math::Random::Secure>,
-and L<Math::TrulyRandom>.
-
-=item read FILEHANDLE,SCALAR,LENGTH,OFFSET
-X<read> X<file, read>
-
-=item read FILEHANDLE,SCALAR,LENGTH
-
-Attempts to read LENGTH I<characters> of data into variable SCALAR
-from the specified FILEHANDLE.  Returns the number of characters
-actually read, C<0> at end of file, or undef if there was an error (in
-the latter case C<$!> is also set).  SCALAR will be grown or shrunk 
-so that the last character actually read is the last character of the
-scalar after the read.
-
-An OFFSET may be specified to place the read data at some place in the
-string other than the beginning.  A negative OFFSET specifies
-placement at that many characters counting backwards from the end of
-the string.  A positive OFFSET greater than the length of SCALAR
-results in the string being padded to the required size with C<"\0">
-bytes before the result of the read is appended.
-
-The call is implemented in terms of either Perl's or your system's native
-fread(3) library function.  To get a true read(2) system call, see
-L<sysread|/sysread FILEHANDLE,SCALAR,LENGTH,OFFSET>.
-
-Note the I<characters>: depending on the status of the filehandle,
-either (8-bit) bytes or characters are read.  By default, all
-filehandles operate on bytes, but for example if the filehandle has
-been opened with the C<:utf8> I/O layer (see L</open>, and the C<open>
-pragma, L<open>), the I/O will operate on UTF8-encoded Unicode
-characters, not bytes.  Similarly for the C<:encoding> pragma:
-in that case pretty much any characters can be read.
-
-=item readdir DIRHANDLE
-X<readdir>
-
-Returns the next directory entry for a directory opened by C<opendir>.
-If used in list context, returns all the rest of the entries in the
-directory.  If there are no more entries, returns the undefined value in
-scalar context and the empty list in list context.
-
-If you're planning to filetest the return values out of a C<readdir>, you'd
-better prepend the directory in question.  Otherwise, because we didn't
-C<chdir> there, it would have been testing the wrong file.
-
-    opendir(my $dh, $some_dir) || die "can't opendir $some_dir: $!";
-    @dots = grep { /^\./ && -f "$some_dir/$_" } readdir($dh);
-    closedir $dh;
-
-As of Perl 5.11.2 you can use a bare C<readdir> in a C<while> loop,
-which will set C<$_> on every iteration.
-
-    opendir(my $dh, $some_dir) || die;
-    while(readdir $dh) {
-        print "$some_dir/$_\n";
-    }
-    closedir $dh;
-
-=item readline EXPR
-
-=item readline
-X<readline> X<gets> X<fgets>
-
-Reads from the filehandle whose typeglob is contained in EXPR (or from
-C<*ARGV> if EXPR is not provided).  In scalar context, each call reads and
-returns the next line until end-of-file is reached, whereupon the
-subsequent call returns C<undef>.  In list context, reads until end-of-file
-is reached and returns a list of lines.  Note that the notion of "line"
-used here is whatever you may have defined with C<$/> or
-C<$INPUT_RECORD_SEPARATOR>).  See L<perlvar/"$/">.
-
-When C<$/> is set to C<undef>, when C<readline> is in scalar
-context (i.e., file slurp mode), and when an empty file is read, it
-returns C<''> the first time, followed by C<undef> subsequently.
-
-This is the internal function implementing the C<< <EXPR> >>
-operator, but you can use it directly.  The C<< <EXPR> >>
-operator is discussed in more detail in L<perlop/"I/O Operators">.
-
-    $line = <STDIN>;
-    $line = readline(*STDIN);    # same thing
-
-If C<readline> encounters an operating system error, C<$!> will be set
-with the corresponding error message.  It can be helpful to check
-C<$!> when you are reading from filehandles you don't trust, such as a
-tty or a socket.  The following example uses the operator form of
-C<readline> and dies if the result is not defined.
-
-    while ( ! eof($fh) ) {
-        defined( $_ = <$fh> ) or die "readline failed: $!";
-        ...
-    }
-
-Note that you have can't handle C<readline> errors that way with the
-C<ARGV> filehandle. In that case, you have to open each element of
-C<@ARGV> yourself since C<eof> handles C<ARGV> differently.
-
-    foreach my $arg (@ARGV) {
-        open(my $fh, $arg) or warn "Can't open $arg: $!";
-
-        while ( ! eof($fh) ) {
-            defined( $_ = <$fh> )
-                or die "readline failed for $arg: $!";
-            ...
-        }
-    }
-
-=item readlink EXPR
-X<readlink>
-
-=item readlink
-
-Returns the value of a symbolic link, if symbolic links are
-implemented.  If not, raises an exception.  If there is a system
-error, returns the undefined value and sets C<$!> (errno).  If EXPR is
-omitted, uses C<$_>.
-
-Portability issues: L<perlport/readlink>.
-
-=item readpipe EXPR
-
-=item readpipe
-X<readpipe>
-
-EXPR is executed as a system command.
-The collected standard output of the command is returned.
-In scalar context, it comes back as a single (potentially
-multi-line) string.  In list context, returns a list of lines
-(however you've defined lines with C<$/> or C<$INPUT_RECORD_SEPARATOR>).
-This is the internal function implementing the C<qx/EXPR/>
-operator, but you can use it directly.  The C<qx/EXPR/>
-operator is discussed in more detail in L<perlop/"I/O Operators">.
-If EXPR is omitted, uses C<$_>.
-
-=item recv SOCKET,SCALAR,LENGTH,FLAGS
-X<recv>
-
-Receives a message on a socket.  Attempts to receive LENGTH characters
-of data into variable SCALAR from the specified SOCKET filehandle.
-SCALAR will be grown or shrunk to the length actually read.  Takes the
-same flags as the system call of the same name.  Returns the address
-of the sender if SOCKET's protocol supports this; returns an empty
-string otherwise.  If there's an error, returns the undefined value.
-This call is actually implemented in terms of recvfrom(2) system call.
-See L<perlipc/"UDP: Message Passing"> for examples.
-
-Note the I<characters>: depending on the status of the socket, either
-(8-bit) bytes or characters are received.  By default all sockets
-operate on bytes, but for example if the socket has been changed using
-binmode() to operate with the C<:encoding(utf8)> I/O layer (see the
-C<open> pragma, L<open>), the I/O will operate on UTF8-encoded Unicode
-characters, not bytes.  Similarly for the C<:encoding> pragma: in that
-case pretty much any characters can be read.
-
-=item redo LABEL
-X<redo>
-
-=item redo
-
-The C<redo> command restarts the loop block without evaluating the
-conditional again.  The C<continue> block, if any, is not executed.  If
-the LABEL is omitted, the command refers to the innermost enclosing
-loop.  Programs that want to lie to themselves about what was just input 
-normally use this command:
-
-    # a simpleminded Pascal comment stripper
-    # (warning: assumes no { or } in strings)
-    LINE: while (<STDIN>) {
-        while (s|({.*}.*){.*}|$1 |) {}
-        s|{.*}| |;
-        if (s|{.*| |) {
-            $front = $_;
-            while (<STDIN>) {
-                if (/}/) {  # end of comment?
-                    s|^|$front\{|;
-                    redo LINE;
-                }
-            }
-        }
-        print;
-    }
-
-C<redo> cannot be used to retry a block that returns a value such as
-C<eval {}>, C<sub {}>, or C<do {}>, and should not be used to exit
-a grep() or map() operation.
-
-Note that a block by itself is semantically identical to a loop
-that executes once.  Thus C<redo> inside such a block will effectively
-turn it into a looping construct.
-
-See also L</continue> for an illustration of how C<last>, C<next>, and
-C<redo> work.
-
-=item ref EXPR
-X<ref> X<reference>
-
-=item ref
-
-Returns a non-empty string if EXPR is a reference, the empty
-string otherwise. If EXPR
-is not specified, C<$_> will be used.  The value returned depends on the
-type of thing the reference is a reference to.
-Builtin types include:
-
-    SCALAR
-    ARRAY
-    HASH
-    CODE
-    REF
-    GLOB
-    LVALUE
-    FORMAT
-    IO
-    VSTRING
-    Regexp
-
-If the referenced object has been blessed into a package, then that package
-name is returned instead.  You can think of C<ref> as a C<typeof> operator.
-
-    if (ref($r) eq "HASH") {
-        print "r is a reference to a hash.\n";
-    }
-    unless (ref($r)) {
-        print "r is not a reference at all.\n";
-    }
-
-The return value C<LVALUE> indicates a reference to an lvalue that is not
-a variable. You get this from taking the reference of function calls like
-C<pos()> or C<substr()>. C<VSTRING> is returned if the reference points
-to a L<version string|perldata/"Version Strings">.
-
-The result C<Regexp> indicates that the argument is a regular expression
-resulting from C<qr//>.
-
-See also L<perlref>.
-
-=item rename OLDNAME,NEWNAME
-X<rename> X<move> X<mv> X<ren>
-
-Changes the name of a file; an existing file NEWNAME will be
-clobbered.  Returns true for success, false otherwise.
-
-Behavior of this function varies wildly depending on your system
-implementation.  For example, it will usually not work across file system
-boundaries, even though the system I<mv> command sometimes compensates
-for this.  Other restrictions include whether it works on directories,
-open files, or pre-existing files.  Check L<perlport> and either the
-rename(2) manpage or equivalent system documentation for details.
-
-For a platform independent C<move> function look at the L<File::Copy>
-module.
-
-Portability issues: L<perlport/rename>.
-
-=item require VERSION
-X<require>
-
-=item require EXPR
-
-=item require
-
-Demands a version of Perl specified by VERSION, or demands some semantics
-specified by EXPR or by C<$_> if EXPR is not supplied.
-
-VERSION may be either a numeric argument such as 5.006, which will be
-compared to C<$]>, or a literal of the form v5.6.1, which will be compared
-to C<$^V> (aka $PERL_VERSION).  An exception is raised if
-VERSION is greater than the version of the current Perl interpreter.
-Compare with L</use>, which can do a similar check at compile time.
-
-Specifying VERSION as a literal of the form v5.6.1 should generally be
-avoided, because it leads to misleading error messages under earlier
-versions of Perl that do not support this syntax.  The equivalent numeric
-version should be used instead.
-
-    require v5.6.1;     # run time version check
-    require 5.6.1;      # ditto
-    require 5.006_001;  # ditto; preferred for backwards compatibility
-
-Otherwise, C<require> demands that a library file be included if it
-hasn't already been included.  The file is included via the do-FILE
-mechanism, which is essentially just a variety of C<eval> with the
-caveat that lexical variables in the invoking script will be invisible
-to the included code.  Has semantics similar to the following subroutine:
-
-    sub require {
-       my ($filename) = @_;
-       if (exists $INC{$filename}) {
-           return 1 if $INC{$filename};
-           die "Compilation failed in require";
-       }
-       my ($realfilename,$result);
-       ITER: {
-           foreach $prefix (@INC) {
-               $realfilename = "$prefix/$filename";
-               if (-f $realfilename) {
-                   $INC{$filename} = $realfilename;
-                   $result = do $realfilename;
-                   last ITER;
-               }
-           }
-           die "Can't find $filename in \@INC";
-       }
-       if ($@) {
-           $INC{$filename} = undef;
-           die $@;
-       } elsif (!$result) {
-           delete $INC{$filename};
-           die "$filename did not return true value";
-       } else {
-           return $result;
-       }
-    }
-
-Note that the file will not be included twice under the same specified
-name.
-
-The file must return true as the last statement to indicate
-successful execution of any initialization code, so it's customary to
-end such a file with C<1;> unless you're sure it'll return true
-otherwise.  But it's better just to put the C<1;>, in case you add more
-statements.
-
-If EXPR is a bareword, the require assumes a "F<.pm>" extension and
-replaces "F<::>" with "F</>" in the filename for you,
-to make it easy to load standard modules.  This form of loading of
-modules does not risk altering your namespace.
-
-In other words, if you try this:
-
-        require Foo::Bar;     # a splendid bareword
-
-The require function will actually look for the "F<Foo/Bar.pm>" file in the
-directories specified in the C<@INC> array.
-
-But if you try this:
-
-        $class = 'Foo::Bar';
-        require $class;       # $class is not a bareword
-    #or
-        require "Foo::Bar";   # not a bareword because of the ""
-
-The require function will look for the "F<Foo::Bar>" file in the @INC array and
-will complain about not finding "F<Foo::Bar>" there.  In this case you can do:
-
-        eval "require $class";
-
-Now that you understand how C<require> looks for files with a
-bareword argument, there is a little extra functionality going on behind
-the scenes.  Before C<require> looks for a "F<.pm>" extension, it will
-first look for a similar filename with a "F<.pmc>" extension. If this file
-is found, it will be loaded in place of any file ending in a "F<.pm>"
-extension.
-
-You can also insert hooks into the import facility by putting Perl code
-directly into the @INC array.  There are three forms of hooks: subroutine
-references, array references, and blessed objects.
-
-Subroutine references are the simplest case.  When the inclusion system
-walks through @INC and encounters a subroutine, this subroutine gets
-called with two parameters, the first a reference to itself, and the
-second the name of the file to be included (e.g., "F<Foo/Bar.pm>").  The
-subroutine should return either nothing or else a list of up to three 
-values in the following order:
-
-=over
-
-=item 1
-
-A filehandle, from which the file will be read.  
-
-=item 2
-
-A reference to a subroutine. If there is no filehandle (previous item),
-then this subroutine is expected to generate one line of source code per
-call, writing the line into C<$_> and returning 1, then finally at end of
-file returning 0.  If there is a filehandle, then the subroutine will be
-called to act as a simple source filter, with the line as read in C<$_>.
-Again, return 1 for each valid line, and 0 after all lines have been
-returned.
-
-=item 3
-
-Optional state for the subroutine. The state is passed in as C<$_[1]>. A
-reference to the subroutine itself is passed in as C<$_[0]>.
-
-=back
-
-If an empty list, C<undef>, or nothing that matches the first 3 values above
-is returned, then C<require> looks at the remaining elements of @INC.
-Note that this filehandle must be a real filehandle (strictly a typeglob
-or reference to a typeglob, whether blessed or unblessed); tied filehandles 
-will be ignored and processing will stop there.
-
-If the hook is an array reference, its first element must be a subroutine
-reference.  This subroutine is called as above, but the first parameter is
-the array reference.  This lets you indirectly pass arguments to
-the subroutine.
-
-In other words, you can write:
-
-    push @INC, \&my_sub;
-    sub my_sub {
-        my ($coderef, $filename) = @_;  # $coderef is \&my_sub
-        ...
-    }
-
-or:
-
-    push @INC, [ \&my_sub, $x, $y, ... ];
-    sub my_sub {
-        my ($arrayref, $filename) = @_;
-        # Retrieve $x, $y, ...
-        my @parameters = @$arrayref[1..$#$arrayref];
-        ...
-    }
-
-If the hook is an object, it must provide an INC method that will be
-called as above, the first parameter being the object itself.  (Note that
-you must fully qualify the sub's name, as unqualified C<INC> is always forced
-into package C<main>.)  Here is a typical code layout:
-
-    # In Foo.pm
-    package Foo;
-    sub new { ... }
-    sub Foo::INC {
-        my ($self, $filename) = @_;
-        ...
-    }
-
-    # In the main program
-    push @INC, Foo->new(...);
-
-These hooks are also permitted to set the %INC entry
-corresponding to the files they have loaded. See L<perlvar/%INC>.
-
-For a yet-more-powerful import facility, see L</use> and L<perlmod>.
-
-=item reset EXPR
-X<reset>
-
-=item reset
-
-Generally used in a C<continue> block at the end of a loop to clear
-variables and reset C<??> searches so that they work again.  The
-expression is interpreted as a list of single characters (hyphens
-allowed for ranges).  All variables and arrays beginning with one of
-those letters are reset to their pristine state.  If the expression is
-omitted, one-match searches (C<?pattern?>) are reset to match again.  
-Only resets variables or searches in the current package.  Always returns
-1.  Examples:
-
-    reset 'X';      # reset all X variables
-    reset 'a-z';    # reset lower case variables
-    reset;          # just reset ?one-time? searches
-
-Resetting C<"A-Z"> is not recommended because you'll wipe out your
-C<@ARGV> and C<@INC> arrays and your C<%ENV> hash.  Resets only package
-variables; lexical variables are unaffected, but they clean themselves
-up on scope exit anyway, so you'll probably want to use them instead.
-See L</my>.
-
-=item return EXPR
-X<return>
-
-=item return
-
-Returns from a subroutine, C<eval>, or C<do FILE> with the value
-given in EXPR.  Evaluation of EXPR may be in list, scalar, or void
-context, depending on how the return value will be used, and the context
-may vary from one execution to the next (see L</wantarray>).  If no EXPR
-is given, returns an empty list in list context, the undefined value in
-scalar context, and (of course) nothing at all in void context.
-
-(In the absence of an explicit C<return>, a subroutine, eval,
-or do FILE automatically returns the value of the last expression
-evaluated.)
-
-=item reverse LIST
-X<reverse> X<rev> X<invert>
-
-In list context, returns a list value consisting of the elements
-of LIST in the opposite order.  In scalar context, concatenates the
-elements of LIST and returns a string value with all characters
-in the opposite order.
-
-    print join(", ", reverse "world", "Hello"); # Hello, world
-
-    print scalar reverse "dlrow ,", "olleH";    # Hello, world
-
-Used without arguments in scalar context, reverse() reverses C<$_>.
-
-    $_ = "dlrow ,olleH";
-    print reverse;                              # No output, list context
-    print scalar reverse;                       # Hello, world
-
-Note that reversing an array to itself (as in C<@a = reverse @a>) will
-preserve non-existent elements whenever possible, i.e., for non magical
-arrays or tied arrays with C<EXISTS> and C<DELETE> methods.
-
-This operator is also handy for inverting a hash, although there are some
-caveats.  If a value is duplicated in the original hash, only one of those
-can be represented as a key in the inverted hash.  Also, this has to
-unwind one hash and build a whole new one, which may take some time
-on a large hash, such as from a DBM file.
-
-    %by_name = reverse %by_address;  # Invert the hash
-
-=item rewinddir DIRHANDLE
-X<rewinddir>
-
-Sets the current position to the beginning of the directory for the
-C<readdir> routine on DIRHANDLE.
-
-Portability issues: L<perlport/rewinddir>.
-
-=item rindex STR,SUBSTR,POSITION
-X<rindex>
-
-=item rindex STR,SUBSTR
-
-Works just like index() except that it returns the position of the I<last>
-occurrence of SUBSTR in STR.  If POSITION is specified, returns the
-last occurrence beginning at or before that position.
-
-=item rmdir FILENAME
-X<rmdir> X<rd> X<directory, remove>
-
-=item rmdir
-
-Deletes the directory specified by FILENAME if that directory is
-empty.  If it succeeds it returns true; otherwise it returns false and
-sets C<$!> (errno).  If FILENAME is omitted, uses C<$_>.
-
-To remove a directory tree recursively (C<rm -rf> on Unix) look at
-the C<rmtree> function of the L<File::Path> module.
-
-=item s///
-
-The substitution operator.  See L<perlop/"Regexp Quote-Like Operators">.
-
-=item say FILEHANDLE LIST
-X<say>
-
-=item say FILEHANDLE
-
-=item say LIST
-
-=item say
-
-Just like C<print>, but implicitly appends a newline.  C<say LIST> is
-simply an abbreviation for C<{ local $\ = "\n"; print LIST }>.  To use
-FILEHANDLE without a LIST to print the contents of C<$_> to it, you must
-use a real filehandle like C<FH>, not an indirect one like C<$fh>.
-
-This keyword is available only when the C<"say"> feature
-is enabled, or when prefixed with C<CORE::>; see
-L<feature>.  Alternately, include a C<use v5.10> or later to the current
-scope.
-
-=item scalar EXPR
-X<scalar> X<context>
-
-Forces EXPR to be interpreted in scalar context and returns the value
-of EXPR.
-
-    @counts = ( scalar @a, scalar @b, scalar @c );
-
-There is no equivalent operator to force an expression to
-be interpolated in list context because in practice, this is never
-needed.  If you really wanted to do so, however, you could use
-the construction C<@{[ (some expression) ]}>, but usually a simple
-C<(some expression)> suffices.
-
-Because C<scalar> is a unary operator, if you accidentally use a
-parenthesized list for the EXPR, this behaves as a scalar comma expression,
-evaluating all but the last element in void context and returning the final
-element evaluated in scalar context.  This is seldom what you want.
-
-The following single statement:
-
-    print uc(scalar(&foo,$bar)),$baz;
-
-is the moral equivalent of these two:
-
-    &foo;
-    print(uc($bar),$baz);
-
-See L<perlop> for more details on unary operators and the comma operator.
-
-=item seek FILEHANDLE,POSITION,WHENCE
-X<seek> X<fseek> X<filehandle, position>
-
-Sets FILEHANDLE's position, just like the C<fseek> call of C<stdio>.
-FILEHANDLE may be an expression whose value gives the name of the
-filehandle.  The values for WHENCE are C<0> to set the new position
-I<in bytes> to POSITION; C<1> to set it to the current position plus
-POSITION; and C<2> to set it to EOF plus POSITION, typically
-negative.  For WHENCE you may use the constants C<SEEK_SET>,
-C<SEEK_CUR>, and C<SEEK_END> (start of the file, current position, end
-of the file) from the L<Fcntl> module.  Returns C<1> on success, false
-otherwise.
-
-Note the I<in bytes>: even if the filehandle has been set to
-operate on characters (for example by using the C<:encoding(utf8)> open
-layer), tell() will return byte offsets, not character offsets
-(because implementing that would render seek() and tell() rather slow).
-
-If you want to position the file for C<sysread> or C<syswrite>, don't use
-C<seek>, because buffering makes its effect on the file's read-write position
-unpredictable and non-portable.  Use C<sysseek> instead.
-
-Due to the rules and rigors of ANSI C, on some systems you have to do a
-seek whenever you switch between reading and writing.  Amongst other
-things, this may have the effect of calling stdio's clearerr(3).
-A WHENCE of C<1> (C<SEEK_CUR>) is useful for not moving the file position:
-
-    seek(TEST,0,1);
-
-This is also useful for applications emulating C<tail -f>.  Once you hit
-EOF on your read and then sleep for a while, you (probably) have to stick in a
-dummy seek() to reset things.  The C<seek> doesn't change the position,
-but it I<does> clear the end-of-file condition on the handle, so that the
-next C<< <FILE> >> makes Perl try again to read something.  (We hope.)
-
-If that doesn't work (some I/O implementations are particularly
-cantankerous), you might need something like this:
-
-    for (;;) {
-        for ($curpos = tell(FILE); $_ = <FILE>;
-             $curpos = tell(FILE)) {
-            # search for some stuff and put it into files
-        }
-        sleep($for_a_while);
-        seek(FILE, $curpos, 0);
-    }
-
-=item seekdir DIRHANDLE,POS
-X<seekdir>
-
-Sets the current position for the C<readdir> routine on DIRHANDLE.  POS
-must be a value returned by C<telldir>.  C<seekdir> also has the same caveats
-about possible directory compaction as the corresponding system library
-routine.
-
-=item select FILEHANDLE
-X<select> X<filehandle, default>
-
-=item select
-
-Returns the currently selected filehandle.  If FILEHANDLE is supplied,
-sets the new current default filehandle for output.  This has two
-effects: first, a C<write> or a C<print> without a filehandle 
-default to this FILEHANDLE.  Second, references to variables related to
-output will refer to this output channel.  
-
-For example, to set the top-of-form format for more than one
-output channel, you might do the following:
-
-    select(REPORT1);
-    $^ = 'report1_top';
-    select(REPORT2);
-    $^ = 'report2_top';
-
-FILEHANDLE may be an expression whose value gives the name of the
-actual filehandle.  Thus:
-
-    $oldfh = select(STDERR); $| = 1; select($oldfh);
-
-Some programmers may prefer to think of filehandles as objects with
-methods, preferring to write the last example as:
-
-    use IO::Handle;
-    STDERR->autoflush(1);
-
-Portability issues: L<perlport/select>.
-
-=item select RBITS,WBITS,EBITS,TIMEOUT
-X<select>
-
-This calls the select(2) syscall with the bit masks specified, which
-can be constructed using C<fileno> and C<vec>, along these lines:
-
-    $rin = $win = $ein = '';
-    vec($rin, fileno(STDIN),  1) = 1;
-    vec($win, fileno(STDOUT), 1) = 1;
-    $ein = $rin | $win;
-
-If you want to select on many filehandles, you may wish to write a
-subroutine like this:
-
-    sub fhbits {
-        my @fhlist = @_;
-        my $bits = "";
-        for my $fh (@fhlist) {
-            vec($bits, fileno($fh), 1) = 1;
-        }
-        return $bits;
-    }
-    $rin = fhbits(*STDIN, *TTY, *MYSOCK);
-
-The usual idiom is:
-
-    ($nfound,$timeleft) =
-      select($rout=$rin, $wout=$win, $eout=$ein, $timeout);
-
-or to block until something becomes ready just do this
-
-    $nfound = select($rout=$rin, $wout=$win, $eout=$ein, undef);
-
-Most systems do not bother to return anything useful in $timeleft, so
-calling select() in scalar context just returns $nfound.
-
-Any of the bit masks can also be undef.  The timeout, if specified, is
-in seconds, which may be fractional.  Note: not all implementations are
-capable of returning the $timeleft.  If not, they always return
-$timeleft equal to the supplied $timeout.
-
-You can effect a sleep of 250 milliseconds this way:
-
-    select(undef, undef, undef, 0.25);
-
-Note that whether C<select> gets restarted after signals (say, SIGALRM)
-is implementation-dependent.  See also L<perlport> for notes on the
-portability of C<select>.
-
-On error, C<select> behaves just like select(2): it returns
--1 and sets C<$!>.
-
-On some Unixes, select(2) may report a socket file descriptor as "ready for
-reading" even when no data is available, and thus any subsequent C<read>
-would block. This can be avoided if you always use O_NONBLOCK on the
-socket. See select(2) and fcntl(2) for further details.
-
-The standard C<IO::Select> module provides a user-friendlier interface
-to C<select>, mostly because it does all the bit-mask work for you.
-
-B<WARNING>: One should not attempt to mix buffered I/O (like C<read>
-or <FH>) with C<select>, except as permitted by POSIX, and even
-then only on POSIX systems.  You have to use C<sysread> instead.
-
-Portability issues: L<perlport/select>.
-
-=item semctl ID,SEMNUM,CMD,ARG
-X<semctl>
-
-Calls the System V IPC function semctl(2).  You'll probably have to say
-
-    use IPC::SysV;
-
-first to get the correct constant definitions.  If CMD is IPC_STAT or
-GETALL, then ARG must be a variable that will hold the returned
-semid_ds structure or semaphore value array.  Returns like C<ioctl>:
-the undefined value for error, "C<0 but true>" for zero, or the actual
-return value otherwise.  The ARG must consist of a vector of native
-short integers, which may be created with C<pack("s!",(0)x$nsem)>.
-See also L<perlipc/"SysV IPC">, C<IPC::SysV>, C<IPC::Semaphore>
-documentation.
-
-Portability issues: L<perlport/semctl>.
-
-=item semget KEY,NSEMS,FLAGS
-X<semget>
-
-Calls the System V IPC function semget(2).  Returns the semaphore id, or
-the undefined value on error.  See also
-L<perlipc/"SysV IPC">, C<IPC::SysV>, C<IPC::SysV::Semaphore>
-documentation.
-
-Portability issues: L<perlport/semget>.
-
-=item semop KEY,OPSTRING
-X<semop>
-
-Calls the System V IPC function semop(2) for semaphore operations
-such as signalling and waiting.  OPSTRING must be a packed array of
-semop structures.  Each semop structure can be generated with
-C<pack("s!3", $semnum, $semop, $semflag)>.  The length of OPSTRING 
-implies the number of semaphore operations.  Returns true if
-successful, false on error.  As an example, the
-following code waits on semaphore $semnum of semaphore id $semid:
-
-    $semop = pack("s!3", $semnum, -1, 0);
-    die "Semaphore trouble: $!\n" unless semop($semid, $semop);
-
-To signal the semaphore, replace C<-1> with C<1>.  See also
-L<perlipc/"SysV IPC">, C<IPC::SysV>, and C<IPC::SysV::Semaphore>
-documentation.
-
-Portability issues: L<perlport/semop>.
-
-=item send SOCKET,MSG,FLAGS,TO
-X<send>
-
-=item send SOCKET,MSG,FLAGS
-
-Sends a message on a socket.  Attempts to send the scalar MSG to the SOCKET
-filehandle.  Takes the same flags as the system call of the same name.  On
-unconnected sockets, you must specify a destination to I<send to>, in which
-case it does a sendto(2) syscall.  Returns the number of characters sent,
-or the undefined value on error.  The sendmsg(2) syscall is currently
-unimplemented.  See L<perlipc/"UDP: Message Passing"> for examples.
-
-Note the I<characters>: depending on the status of the socket, either
-(8-bit) bytes or characters are sent.  By default all sockets operate
-on bytes, but for example if the socket has been changed using
-binmode() to operate with the C<:encoding(utf8)> I/O layer (see
-L</open>, or the C<open> pragma, L<open>), the I/O will operate on UTF-8
-encoded Unicode characters, not bytes.  Similarly for the C<:encoding>
-pragma: in that case pretty much any characters can be sent.
-
-=item setpgrp PID,PGRP
-X<setpgrp> X<group>
-
-Sets the current process group for the specified PID, C<0> for the current
-process.  Raises an exception when used on a machine that doesn't
-implement POSIX setpgid(2) or BSD setpgrp(2).  If the arguments are omitted,
-it defaults to C<0,0>.  Note that the BSD 4.2 version of C<setpgrp> does not
-accept any arguments, so only C<setpgrp(0,0)> is portable.  See also
-C<POSIX::setsid()>.
-
-Portability issues: L<perlport/setpgrp>.
-
-=item setpriority WHICH,WHO,PRIORITY
-X<setpriority> X<priority> X<nice> X<renice>
-
-Sets the current priority for a process, a process group, or a user.
-(See setpriority(2).)  Raises an exception when used on a machine
-that doesn't implement setpriority(2).
-
-Portability issues: L<perlport/setpriority>.
-
-=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
-X<setsockopt>
-
-Sets the socket option requested.  Returns C<undef> on error.
-Use integer constants provided by the C<Socket> module for
-LEVEL and OPNAME.  Values for LEVEL can also be obtained from
-getprotobyname.  OPTVAL might either be a packed string or an integer.
-An integer OPTVAL is shorthand for pack("i", OPTVAL).
-
-An example disabling Nagle's algorithm on a socket:
-
-    use Socket qw(IPPROTO_TCP TCP_NODELAY);
-    setsockopt($socket, IPPROTO_TCP, TCP_NODELAY, 1);
-
-Portability issues: L<perlport/setsockopt>.
-
-=item shift ARRAY
-X<shift>
-
-=item shift EXPR
-
-=item shift
-
-Shifts the first value of the array off and returns it, shortening the
-array by 1 and moving everything down.  If there are no elements in the
-array, returns the undefined value.  If ARRAY is omitted, shifts the
-C<@_> array within the lexical scope of subroutines and formats, and the
-C<@ARGV> array outside a subroutine and also within the lexical scopes
-established by the C<eval STRING>, C<BEGIN {}>, C<INIT {}>, C<CHECK {}>,
-C<UNITCHECK {}>, and C<END {}> constructs.
-
-Starting with Perl 5.14, C<shift> can take a scalar EXPR, which must hold a
-reference to an unblessed array.  The argument will be dereferenced
-automatically.  This aspect of C<shift> is considered highly experimental.
-The exact behaviour may change in a future version of Perl.
-
-See also C<unshift>, C<push>, and C<pop>.  C<shift> and C<unshift> do the
-same thing to the left end of an array that C<pop> and C<push> do to the
-right end.
-
-=item shmctl ID,CMD,ARG
-X<shmctl>
-
-Calls the System V IPC function shmctl.  You'll probably have to say
-
-    use IPC::SysV;
-
-first to get the correct constant definitions.  If CMD is C<IPC_STAT>,
-then ARG must be a variable that will hold the returned C<shmid_ds>
-structure.  Returns like ioctl: C<undef> for error; "C<0> but
-true" for zero; and the actual return value otherwise.
-See also L<perlipc/"SysV IPC"> and C<IPC::SysV> documentation.
-
-Portability issues: L<perlport/shmctl>.
-
-=item shmget KEY,SIZE,FLAGS
-X<shmget>
-
-Calls the System V IPC function shmget.  Returns the shared memory
-segment id, or C<undef> on error.
-See also L<perlipc/"SysV IPC"> and C<IPC::SysV> documentation.
-
-Portability issues: L<perlport/shmget>.
-
-=item shmread ID,VAR,POS,SIZE
-X<shmread>
-X<shmwrite>
-
-=item shmwrite ID,STRING,POS,SIZE
-
-Reads or writes the System V shared memory segment ID starting at
-position POS for size SIZE by attaching to it, copying in/out, and
-detaching from it.  When reading, VAR must be a variable that will
-hold the data read.  When writing, if STRING is too long, only SIZE
-bytes are used; if STRING is too short, nulls are written to fill out
-SIZE bytes.  Return true if successful, false on error.
-shmread() taints the variable. See also L<perlipc/"SysV IPC">,
-C<IPC::SysV>, and the C<IPC::Shareable> module from CPAN.
-
-Portability issues: L<perlport/shmread> and L<perlport/shmwrite>.
-
-=item shutdown SOCKET,HOW
-X<shutdown>
-
-Shuts down a socket connection in the manner indicated by HOW, which
-has the same interpretation as in the syscall of the same name.
-
-    shutdown(SOCKET, 0);    # I/we have stopped reading data
-    shutdown(SOCKET, 1);    # I/we have stopped writing data
-    shutdown(SOCKET, 2);    # I/we have stopped using this socket
-
-This is useful with sockets when you want to tell the other
-side you're done writing but not done reading, or vice versa.
-It's also a more insistent form of close because it also
-disables the file descriptor in any forked copies in other
-processes.
-
-Returns C<1> for success; on error, returns C<undef> if
-the first argument is not a valid filehandle, or returns C<0> and sets
-C<$!> for any other failure.
-
-=item sin EXPR
-X<sin> X<sine> X<asin> X<arcsine>
-
-=item sin
-
-Returns the sine of EXPR (expressed in radians).  If EXPR is omitted,
-returns sine of C<$_>.
-
-For the inverse sine operation, you may use the C<Math::Trig::asin>
-function, or use this relation:
-
-    sub asin { atan2($_[0], sqrt(1 - $_[0] * $_[0])) }
-
-=item sleep EXPR
-X<sleep> X<pause>
-
-=item sleep
-
-Causes the script to sleep for (integer) EXPR seconds, or forever if no 
-argument is given.  Returns the integer number of seconds actually slept.  
-
-May be interrupted if the process receives a signal such as C<SIGALRM>.
-
-    eval {
-        local $SIG{ALARM} = sub { die "Alarm!\n" };
-        sleep;
-    };
-    die $@ unless $@ eq "Alarm!\n";
-
-You probably cannot mix C<alarm> and C<sleep> calls, because C<sleep>
-is often implemented using C<alarm>.
-
-On some older systems, it may sleep up to a full second less than what
-you requested, depending on how it counts seconds.  Most modern systems
-always sleep the full amount.  They may appear to sleep longer than that,
-however, because your process might not be scheduled right away in a
-busy multitasking system.
-
-For delays of finer granularity than one second, the Time::HiRes module
-(from CPAN, and starting from Perl 5.8 part of the standard
-distribution) provides usleep().  You may also use Perl's four-argument
-version of select() leaving the first three arguments undefined, or you
-might be able to use the C<syscall> interface to access setitimer(2) if
-your system supports it. See L<perlfaq8> for details.
-
-See also the POSIX module's C<pause> function.
-
-=item socket SOCKET,DOMAIN,TYPE,PROTOCOL
-X<socket>
-
-Opens a socket of the specified kind and attaches it to filehandle
-SOCKET.  DOMAIN, TYPE, and PROTOCOL are specified the same as for
-the syscall of the same name.  You should C<use Socket> first
-to get the proper definitions imported.  See the examples in
-L<perlipc/"Sockets: Client/Server Communication">.
-
-On systems that support a close-on-exec flag on files, the flag will
-be set for the newly opened file descriptor, as determined by the
-value of $^F.  See L<perlvar/$^F>.
-
-=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
-X<socketpair>
-
-Creates an unnamed pair of sockets in the specified domain, of the
-specified type.  DOMAIN, TYPE, and PROTOCOL are specified the same as
-for the syscall of the same name.  If unimplemented, raises an exception.
-Returns true if successful.
-
-On systems that support a close-on-exec flag on files, the flag will
-be set for the newly opened file descriptors, as determined by the value
-of $^F.  See L<perlvar/$^F>.
-
-Some systems defined C<pipe> in terms of C<socketpair>, in which a call
-to C<pipe(Rdr, Wtr)> is essentially:
-
-    use Socket;
-    socketpair(Rdr, Wtr, AF_UNIX, SOCK_STREAM, PF_UNSPEC);
-    shutdown(Rdr, 1);        # no more writing for reader
-    shutdown(Wtr, 0);        # no more reading for writer
-
-See L<perlipc> for an example of socketpair use.  Perl 5.8 and later will
-emulate socketpair using IP sockets to localhost if your system implements
-sockets but not socketpair.
-
-Portability issues: L<perlport/socketpair>.
-
-=item sort SUBNAME LIST
-X<sort> X<qsort> X<quicksort> X<mergesort>
-
-=item sort BLOCK LIST
-
-=item sort LIST
-
-In list context, this sorts the LIST and returns the sorted list value.
-In scalar context, the behaviour of C<sort()> is undefined.
-
-If SUBNAME or BLOCK is omitted, C<sort>s in standard string comparison
-order.  If SUBNAME is specified, it gives the name of a subroutine
-that returns an integer less than, equal to, or greater than C<0>,
-depending on how the elements of the list are to be ordered.  (The 
-C<< <=> >> and C<cmp> operators are extremely useful in such routines.)
-SUBNAME may be a scalar variable name (unsubscripted), in which case
-the value provides the name of (or a reference to) the actual
-subroutine to use.  In place of a SUBNAME, you can provide a BLOCK as
-an anonymous, in-line sort subroutine.
-
-If the subroutine's prototype is C<($$)>, the elements to be compared are
-passed by reference in C<@_>, as for a normal subroutine.  This is slower
-than unprototyped subroutines, where the elements to be compared are passed
-into the subroutine as the package global variables $a and $b (see example
-below).  Note that in the latter case, it is usually highly counter-productive
-to declare $a and $b as lexicals.
-
-If the subroutine is an XSUB, the elements to be compared are pushed on to
-the stack, the way arguments are usually passed to XSUBs.  $a and $b are
-not set.
-
-The values to be compared are always passed by reference and should not
-be modified.
-
-You also cannot exit out of the sort block or subroutine using any of the
-loop control operators described in L<perlsyn> or with C<goto>.
-
-When C<use locale> is in effect, C<sort LIST> sorts LIST according to the
-current collation locale.  See L<perllocale>.
-
-sort() returns aliases into the original list, much as a for loop's index
-variable aliases the list elements.  That is, modifying an element of a
-list returned by sort() (for example, in a C<foreach>, C<map> or C<grep>)
-actually modifies the element in the original list.  This is usually
-something to be avoided when writing clear code.
-
-Perl 5.6 and earlier used a quicksort algorithm to implement sort.
-That algorithm was not stable, so I<could> go quadratic.  (A I<stable> sort
-preserves the input order of elements that compare equal.  Although
-quicksort's run time is O(NlogN) when averaged over all arrays of
-length N, the time can be O(N**2), I<quadratic> behavior, for some
-inputs.)  In 5.7, the quicksort implementation was replaced with
-a stable mergesort algorithm whose worst-case behavior is O(NlogN).
-But benchmarks indicated that for some inputs, on some platforms,
-the original quicksort was faster.  5.8 has a sort pragma for
-limited control of the sort.  Its rather blunt control of the
-underlying algorithm may not persist into future Perls, but the
-ability to characterize the input or output in implementation
-independent ways quite probably will.  See L<the sort pragma|sort>.
-
-Examples:
-
-    # sort lexically
-    @articles = sort @files;
-    
-    # same thing, but with explicit sort routine
-    @articles = sort {$a cmp $b} @files;
-    
-    # now case-insensitively
-    @articles = sort {uc($a) cmp uc($b)} @files;
-    
-    # same thing in reversed order
-    @articles = sort {$b cmp $a} @files;
-    
-    # sort numerically ascending
-    @articles = sort {$a <=> $b} @files;
-    
-    # sort numerically descending
-    @articles = sort {$b <=> $a} @files;
-    
-    # this sorts the %age hash by value instead of key
-    # using an in-line function
-    @eldest = sort { $age{$b} <=> $age{$a} } keys %age;
-    
-    # sort using explicit subroutine name
-    sub byage {
-        $age{$a} <=> $age{$b};  # presuming numeric
-    }
-    @sortedclass = sort byage @class;
-    
-    sub backwards { $b cmp $a }
-    @harry  = qw(dog cat x Cain Abel);
-    @george = qw(gone chased yz Punished Axed);
-    print sort @harry;
-        # prints AbelCaincatdogx
-    print sort backwards @harry;
-        # prints xdogcatCainAbel
-    print sort @george, 'to', @harry;
-        # prints AbelAxedCainPunishedcatchaseddoggonetoxyz
-
-    # inefficiently sort by descending numeric compare using
-    # the first integer after the first = sign, or the
-    # whole record case-insensitively otherwise
-
-    my @new = sort {
-        ($b =~ /=(\d+)/)[0] <=> ($a =~ /=(\d+)/)[0]
-                            ||
-                    uc($a)  cmp  uc($b)
-    } @old;
-
-    # same thing, but much more efficiently;
-    # we'll build auxiliary indices instead
-    # for speed
-    my @nums = @caps = ();
-    for (@old) {
-        push @nums, ( /=(\d+)/ ? $1 : undef );
-        push @caps, uc($_);
-    }
-
-    my @new = @old[ sort {
-                           $nums[$b] <=> $nums[$a]
-                                    ||
-                           $caps[$a] cmp $caps[$b]
-                         } 0..$#old
-                  ];
-
-    # same thing, but without any temps
-    @new = map { $_->[0] }
-           sort { $b->[1] <=> $a->[1]
-                           ||
-                  $a->[2] cmp $b->[2]
-           } map { [$_, /=(\d+)/, uc($_)] } @old;
-
-    # using a prototype allows you to use any comparison subroutine
-    # as a sort subroutine (including other package's subroutines)
-    package other;
-    sub backwards ($$) { $_[1] cmp $_[0]; }  # $a and $b are not set here
-    
-    package main;
-    @new = sort other::backwards @old;
-    
-    # guarantee stability, regardless of algorithm
-    use sort 'stable';
-    @new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
-    
-    # force use of mergesort (not portable outside Perl 5.8)
-    use sort '_mergesort';  # note discouraging _
-    @new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
-
-Warning: syntactical care is required when sorting the list returned from
-a function. If you want to sort the list returned by the function call
-C<find_records(@key)>, you can use:
-
-    @contact = sort { $a cmp $b } find_records @key;
-    @contact = sort +find_records(@key);
-    @contact = sort &find_records(@key);
-    @contact = sort(find_records(@key));
-
-If instead you want to sort the array @key with the comparison routine
-C<find_records()> then you can use:
-
-    @contact = sort { find_records() } @key;
-    @contact = sort find_records(@key);
-    @contact = sort(find_records @key);
-    @contact = sort(find_records (@key));
-
-If you're using strict, you I<must not> declare $a
-and $b as lexicals.  They are package globals.  That means
-that if you're in the C<main> package and type
-
-    @articles = sort {$b <=> $a} @files;
-
-then C<$a> and C<$b> are C<$main::a> and C<$main::b> (or C<$::a> and C<$::b>),
-but if you're in the C<FooPack> package, it's the same as typing
-
-    @articles = sort {$FooPack::b <=> $FooPack::a} @files;
-
-The comparison function is required to behave.  If it returns
-inconsistent results (sometimes saying C<$x[1]> is less than C<$x[2]> and
-sometimes saying the opposite, for example) the results are not
-well-defined.
-
-Because C<< <=> >> returns C<undef> when either operand is C<NaN>
-(not-a-number), be careful when sorting with a
-comparison function like C<< $a <=> $b >> any lists that might contain a
-C<NaN>.  The following example takes advantage that C<NaN != NaN> to
-eliminate any C<NaN>s from the input list.
-
-    @result = sort { $a <=> $b } grep { $_ == $_ } @input;
-
-=item splice ARRAY or EXPR,OFFSET,LENGTH,LIST
-X<splice>
-
-=item splice ARRAY or EXPR,OFFSET,LENGTH
-
-=item splice ARRAY or EXPR,OFFSET
-
-=item splice ARRAY or EXPR
-
-Removes the elements designated by OFFSET and LENGTH from an array, and
-replaces them with the elements of LIST, if any.  In list context,
-returns the elements removed from the array.  In scalar context,
-returns the last element removed, or C<undef> if no elements are
-removed.  The array grows or shrinks as necessary.
-If OFFSET is negative then it starts that far from the end of the array.
-If LENGTH is omitted, removes everything from OFFSET onward.
-If LENGTH is negative, removes the elements from OFFSET onward
-except for -LENGTH elements at the end of the array.
-If both OFFSET and LENGTH are omitted, removes everything. If OFFSET is
-past the end of the array, Perl issues a warning, and splices at the
-end of the array.
-
-The following equivalences hold (assuming C<< $#a >= $i >> )
-
-    push(@a,$x,$y)      splice(@a,@a,0,$x,$y)
-    pop(@a)             splice(@a,-1)
-    shift(@a)           splice(@a,0,1)
-    unshift(@a,$x,$y)   splice(@a,0,0,$x,$y)
-    $a[$i] = $y         splice(@a,$i,1,$y)
-
-Example, assuming array lengths are passed before arrays:
-
-    sub aeq {  # compare two list values
-        my(@a) = splice(@_,0,shift);
-        my(@b) = splice(@_,0,shift);
-        return 0 unless @a == @b;  # same len?
-        while (@a) {
-            return 0 if pop(@a) ne pop(@b);
-        }
-        return 1;
-    }
-    if (&aeq($len,@foo[1..$len],0+@bar,@bar)) { ... }
-
-Starting with Perl 5.14, C<splice> can take scalar EXPR, which must hold a
-reference to an unblessed array.  The argument will be dereferenced
-automatically.  This aspect of C<splice> is considered highly experimental.
-The exact behaviour may change in a future version of Perl.
-
-=item split /PATTERN/,EXPR,LIMIT
-X<split>
-
-=item split /PATTERN/,EXPR
-
-=item split /PATTERN/
-
-=item split
-
-Splits the string EXPR into a list of strings and returns that list.  By
-default, empty leading fields are preserved, and empty trailing ones are
-deleted.  (If all fields are empty, they are considered to be trailing.)
-
-In scalar context, returns the number of fields found.
-
-If EXPR is omitted, splits the C<$_> string.  If PATTERN is also omitted,
-splits on whitespace (after skipping any leading whitespace).  Anything
-matching PATTERN is taken to be a delimiter separating the fields.  (Note
-that the delimiter may be longer than one character.)
-
-If LIMIT is specified and positive, it represents the maximum number
-of fields the EXPR will be split into, though the actual number of
-fields returned depends on the number of times PATTERN matches within
-EXPR.  If LIMIT is unspecified or zero, trailing null fields are
-stripped (which potential users of C<pop> would do well to remember).
-If LIMIT is negative, it is treated as if an arbitrarily large LIMIT
-had been specified.  Note that splitting an EXPR that evaluates to the
-empty string always returns the empty list, regardless of the LIMIT
-specified.
-
-A pattern matching the empty string (not to be confused with
-an empty pattern C<//>, which is just one member of the set of patterns
-matching the empty string), splits EXPR into individual
-characters.  For example:
-
-    print join(':', split(/ */, 'hi there')), "\n";
-
-produces the output 'h:i:t:h:e:r:e'.
-
-As a special case for C<split>, the empty pattern C<//> specifically
-matches the empty string; this is not be confused with the normal use
-of an empty pattern to mean the last successful match.  So to split
-a string into individual characters, the following:
-
-    print join(':', split(//, 'hi there')), "\n";
-
-produces the output 'h:i: :t:h:e:r:e'.
-
-Empty leading fields are produced when there are positive-width matches at
-the beginning of the string; a zero-width match at the beginning of
-the string does not produce an empty field. For example:
-
-   print join(':', split(/(?=\w)/, 'hi there!'));
-
-produces the output 'h:i :t:h:e:r:e!'. Empty trailing fields, on the other
-hand, are produced when there is a match at the end of the string (and
-when LIMIT is given and is not 0), regardless of the length of the match.
-For example:
-
-   print join(':', split(//,   'hi there!', -1)), "\n";
-   print join(':', split(/\W/, 'hi there!', -1)), "\n";
-
-produce the output 'h:i: :t:h:e:r:e:!:' and 'hi:there:', respectively,
-both with an empty trailing field.
-
-The LIMIT parameter can be used to split a line partially
-
-    ($login, $passwd, $remainder) = split(/:/, $_, 3);
-
-When assigning to a list, if LIMIT is omitted, or zero, Perl supplies
-a LIMIT one larger than the number of variables in the list, to avoid
-unnecessary work.  For the list above LIMIT would have been 4 by
-default.  In time critical applications it behooves you not to split
-into more fields than you really need.
-
-If the PATTERN contains parentheses, additional list elements are
-created from each matching substring in the delimiter.
-
-    split(/([,-])/, "1-10,20", 3);
-
-produces the list value
-
-    (1, '-', 10, ',', 20)
-
-If you had the entire header of a normal Unix email message in $header,
-you could split it up into fields and their values this way:
-
-    $header =~ s/\n(?=\s)//g;  # fix continuation lines
-    %hdrs   =  (UNIX_FROM => split /^(\S*?):\s*/m, $header);
-
-The pattern C</PATTERN/> may be replaced with an expression to specify
-patterns that vary at runtime.  (To do runtime compilation only once,
-use C</$variable/o>.)
-
-As a special case, specifying a PATTERN of space (S<C<' '>>) will split on
-white space just as C<split> with no arguments does.  Thus, S<C<split(' ')>> can
-be used to emulate B<awk>'s default behavior, whereas S<C<split(/ /)>>
-will give you as many initial null fields (empty string) as there are leading spaces.
-A C<split> on C</\s+/> is like a S<C<split(' ')>> except that any leading
-whitespace produces a null first field.  A C<split> with no arguments
-really does a S<C<split(' ', $_)>> internally.
-
-A PATTERN of C</^/> is treated as if it were C</^/m>, since it isn't
-much use otherwise.
-
-Example:
-
-    open(PASSWD, '/etc/passwd');
-    while (<PASSWD>) {
-        chomp;
-        ($login, $passwd, $uid, $gid,
-         $gcos, $home, $shell) = split(/:/);
-        #...
-    }
-
-As with regular pattern matching, any capturing parentheses that are not
-matched in a C<split()> will be set to C<undef> when returned:
-
-    @fields = split /(A)|B/, "1A2B3";
-    # @fields is (1, 'A', 2, undef, 3)
-
-=item sprintf FORMAT, LIST
-X<sprintf>
-
-Returns a string formatted by the usual C<printf> conventions of the C
-library function C<sprintf>.  See below for more details
-and see L<sprintf(3)> or L<printf(3)> on your system for an explanation of
-the general principles.
-
-For example:
-
-        # Format number with up to 8 leading zeroes
-        $result = sprintf("%08d", $number);
-
-        # Round number to 3 digits after decimal point
-        $rounded = sprintf("%.3f", $number);
-
-Perl does its own C<sprintf> formatting: it emulates the C
-function sprintf(3), but doesn't use it except for floating-point
-numbers, and even then only standard modifiers are allowed.  
-Non-standard extensions in your local sprintf(3) are 
-therefore unavailable from Perl.
-
-Unlike C<printf>, C<sprintf> does not do what you probably mean when you
-pass it an array as your first argument. The array is given scalar context,
-and instead of using the 0th element of the array as the format, Perl will
-use the count of elements in the array as the format, which is almost never
-useful.
-
-Perl's C<sprintf> permits the following universally-known conversions:
-
-   %%    a percent sign
-   %c    a character with the given number
-   %s    a string
-   %d    a signed integer, in decimal
-   %u    an unsigned integer, in decimal
-   %o    an unsigned integer, in octal
-   %x    an unsigned integer, in hexadecimal
-   %e    a floating-point number, in scientific notation
-   %f    a floating-point number, in fixed decimal notation
-   %g    a floating-point number, in %e or %f notation
-
-In addition, Perl permits the following widely-supported conversions:
-
-   %X    like %x, but using upper-case letters
-   %E    like %e, but using an upper-case "E"
-   %G    like %g, but with an upper-case "E" (if applicable)
-   %b    an unsigned integer, in binary
-   %B    like %b, but using an upper-case "B" with the # flag
-   %p    a pointer (outputs the Perl value's address in hexadecimal)
-   %n    special: *stores* the number of characters output so far
-         into the next variable in the parameter list
-
-Finally, for backward (and we do mean "backward") compatibility, Perl
-permits these unnecessary but widely-supported conversions:
-
-   %i    a synonym for %d
-   %D    a synonym for %ld
-   %U    a synonym for %lu
-   %O    a synonym for %lo
-   %F    a synonym for %f
-
-Note that the number of exponent digits in the scientific notation produced
-by C<%e>, C<%E>, C<%g> and C<%G> for numbers with the modulus of the
-exponent less than 100 is system-dependent: it may be three or less
-(zero-padded as necessary).  In other words, 1.23 times ten to the
-99th may be either "1.23e99" or "1.23e099".
-
-Between the C<%> and the format letter, you may specify several
-additional attributes controlling the interpretation of the format.
-In order, these are:
-
-=over 4
-
-=item format parameter index
-
-An explicit format parameter index, such as C<2$>. By default sprintf
-will format the next unused argument in the list, but this allows you
-to take the arguments out of order:
-
-  printf '%2$d %1$d', 12, 34;      # prints "34 12"
-  printf '%3$d %d %1$d', 1, 2, 3;  # prints "3 1 1"
-
-=item flags
-
-one or more of:
-
-   space   prefix non-negative number with a space
-   +       prefix non-negative number with a plus sign
-   -       left-justify within the field
-   0       use zeros, not spaces, to right-justify
-   #       ensure the leading "0" for any octal,
-           prefix non-zero hexadecimal with "0x" or "0X",
-           prefix non-zero binary with "0b" or "0B"
-
-For example:
-
-  printf '<% d>',  12;   # prints "< 12>"
-  printf '<%+d>',  12;   # prints "<+12>"
-  printf '<%6s>',  12;   # prints "<    12>"
-  printf '<%-6s>', 12;   # prints "<12    >"
-  printf '<%06s>', 12;   # prints "<000012>"
-  printf '<%#o>',  12;   # prints "<014>"
-  printf '<%#x>',  12;   # prints "<0xc>"
-  printf '<%#X>',  12;   # prints "<0XC>"
-  printf '<%#b>',  12;   # prints "<0b1100>"
-  printf '<%#B>',  12;   # prints "<0B1100>"
-
-When a space and a plus sign are given as the flags at once,
-a plus sign is used to prefix a positive number.
-
-  printf '<%+ d>', 12;   # prints "<+12>"
-  printf '<% +d>', 12;   # prints "<+12>"
-
-When the # flag and a precision are given in the %o conversion,
-the precision is incremented if it's necessary for the leading "0".
-
-  printf '<%#.5o>', 012;      # prints "<00012>"
-  printf '<%#.5o>', 012345;   # prints "<012345>"
-  printf '<%#.0o>', 0;        # prints "<0>"
-
-=item vector flag
-
-This flag tells Perl to interpret the supplied string as a vector of
-integers, one for each character in the string. Perl applies the format to
-each integer in turn, then joins the resulting strings with a separator (a
-dot C<.> by default). This can be useful for displaying ordinal values of
-characters in arbitrary strings:
-
-  printf "%vd", "AB\x{100}";           # prints "65.66.256"
-  printf "version is v%vd\n", $^V;     # Perl's version
-
-Put an asterisk C<*> before the C<v> to override the string to
-use to separate the numbers:
-
-  printf "address is %*vX\n", ":", $addr;   # IPv6 address
-  printf "bits are %0*v8b\n", " ", $bits;   # random bitstring
-
-You can also explicitly specify the argument number to use for
-the join string using something like C<*2$v>; for example:
-
-  printf '%*4$vX %*4$vX %*4$vX', @addr[1..3], ":";   # 3 IPv6 addresses
-
-=item (minimum) width
-
-Arguments are usually formatted to be only as wide as required to
-display the given value. You can override the width by putting
-a number here, or get the width from the next argument (with C<*>)
-or from a specified argument (e.g., with C<*2$>):
-
-  printf "<%s>", "a";       # prints "<a>"
-  printf "<%6s>", "a";      # prints "<     a>"
-  printf "<%*s>", 6, "a";   # prints "<     a>"
-  printf "<%*2$s>", "a", 6; # prints "<     a>"
-  printf "<%2s>", "long";   # prints "<long>" (does not truncate)
-
-If a field width obtained through C<*> is negative, it has the same
-effect as the C<-> flag: left-justification.
-
-=item precision, or maximum width
-X<precision>
-
-You can specify a precision (for numeric conversions) or a maximum
-width (for string conversions) by specifying a C<.> followed by a number.
-For floating-point formats except C<g> and C<G>, this specifies
-how many places right of the decimal point to show (the default being 6).
-For example:
-
-  # these examples are subject to system-specific variation
-  printf '<%f>', 1;    # prints "<1.000000>"
-  printf '<%.1f>', 1;  # prints "<1.0>"
-  printf '<%.0f>', 1;  # prints "<1>"
-  printf '<%e>', 10;   # prints "<1.000000e+01>"
-  printf '<%.1e>', 10; # prints "<1.0e+01>"
-
-For "g" and "G", this specifies the maximum number of digits to show,
-including those prior to the decimal point and those after it; for 
-example:
-
-  # These examples are subject to system-specific variation.
-  printf '<%g>', 1;        # prints "<1>"
-  printf '<%.10g>', 1;     # prints "<1>"
-  printf '<%g>', 100;      # prints "<100>"
-  printf '<%.1g>', 100;    # prints "<1e+02>"
-  printf '<%.2g>', 100.01; # prints "<1e+02>"
-  printf '<%.5g>', 100.01; # prints "<100.01>"
-  printf '<%.4g>', 100.01; # prints "<100>"
-
-For integer conversions, specifying a precision implies that the
-output of the number itself should be zero-padded to this width,
-where the 0 flag is ignored:
-
-  printf '<%.6d>', 1;      # prints "<000001>"
-  printf '<%+.6d>', 1;     # prints "<+000001>"
-  printf '<%-10.6d>', 1;   # prints "<000001    >"
-  printf '<%10.6d>', 1;    # prints "<    000001>"
-  printf '<%010.6d>', 1;   # prints "<    000001>"
-  printf '<%+10.6d>', 1;   # prints "<   +000001>"
-
-  printf '<%.6x>', 1;      # prints "<000001>"
-  printf '<%#.6x>', 1;     # prints "<0x000001>"
-  printf '<%-10.6x>', 1;   # prints "<000001    >"
-  printf '<%10.6x>', 1;    # prints "<    000001>"
-  printf '<%010.6x>', 1;   # prints "<    000001>"
-  printf '<%#10.6x>', 1;   # prints "<  0x000001>"
-
-For string conversions, specifying a precision truncates the string
-to fit the specified width:
-
-  printf '<%.5s>', "truncated";   # prints "<trunc>"
-  printf '<%10.5s>', "truncated"; # prints "<     trunc>"
-
-You can also get the precision from the next argument using C<.*>:
-
-  printf '<%.6x>', 1;       # prints "<000001>"
-  printf '<%.*x>', 6, 1;    # prints "<000001>"
-
-If a precision obtained through C<*> is negative, it counts
-as having no precision at all.
-
-  printf '<%.*s>',  7, "string";   # prints "<string>"
-  printf '<%.*s>',  3, "string";   # prints "<str>"
-  printf '<%.*s>',  0, "string";   # prints "<>"
-  printf '<%.*s>', -1, "string";   # prints "<string>"
-
-  printf '<%.*d>',  1, 0;   # prints "<0>"
-  printf '<%.*d>',  0, 0;   # prints "<>"
-  printf '<%.*d>', -1, 0;   # prints "<0>"
-
-You cannot currently get the precision from a specified number,
-but it is intended that this will be possible in the future, for
-example using C<.*2$>:
-
-  printf "<%.*2$x>", 1, 6;   # INVALID, but in future will print "<000001>"
-
-=item size
-
-For numeric conversions, you can specify the size to interpret the
-number as using C<l>, C<h>, C<V>, C<q>, C<L>, or C<ll>. For integer
-conversions (C<d u o x X b i D U O>), numbers are usually assumed to be
-whatever the default integer size is on your platform (usually 32 or 64
-bits), but you can override this to use instead one of the standard C types,
-as supported by the compiler used to build Perl:
-
-   hh          interpret integer as C type "char" or "unsigned char"
-	       on Perl 5.14 or later
-   h           interpret integer as C type "short" or "unsigned short"
-   j	       interpret integer as C type "intmax_t" on Perl 5.14 
-	       or later, and only with a C99 compiler (unportable)
-   l           interpret integer as C type "long" or "unsigned long"
-   q, L, or ll interpret integer as C type "long long", "unsigned long long",
-               or "quad" (typically 64-bit integers)
-   t	       interpret integer as C type "ptrdiff_t" on Perl 5.14 or later
-   z	       interpret integer as C type "size_t" on Perl 5.14 or later
-
-As of 5.14, none of these raises an exception if they are not supported on
-your platform.  However, if warnings are enabled, a warning of the
-C<printf> warning class is issued on an unsupported conversion flag.  
-Should you instead prefer an exception, do this:
-
-    use warnings FATAL => "printf";
-
-If you would like to know about a version dependency before you
-start running the program, put something like this at its top:
-
-    use 5.014;  # for hh/j/t/z/ printf modifiers
-
-You can find out whether your Perl supports quads via L<Config>:
-
-    use Config;
-    if ($Config{use64bitint} eq "define" || $Config{longsize} >= 8) {
-        print "Nice quads!\n";
-    }
-
-For floating-point conversions (C<e f g E F G>), numbers are usually assumed
-to be the default floating-point size on your platform (double or long double),
-but you can force "long double" with C<q>, C<L>, or C<ll> if your
-platform supports them. You can find out whether your Perl supports long
-doubles via L<Config>:
-
-    use Config;
-    print "long doubles\n" if $Config{d_longdbl} eq "define";
-
-You can find out whether Perl considers "long double" to be the default
-floating-point size to use on your platform via L<Config>:
-
-    use Config;
-    if ($Config{uselongdouble} eq "define") {
-	print "long doubles by default\n";
-    }
-
-It can also be that long doubles and doubles are the same thing:
-
-        use Config;
-        ($Config{doublesize} == $Config{longdblsize}) &&
-                print "doubles are long doubles\n";
-
-The size specifier C<V> has no effect for Perl code, but is supported for
-compatibility with XS code.  It means "use the standard size for a Perl
-integer or floating-point number", which is the default.
-
-=item order of arguments
-
-Normally, sprintf() takes the next unused argument as the value to
-format for each format specification. If the format specification
-uses C<*> to require additional arguments, these are consumed from
-the argument list in the order they appear in the format
-specification I<before> the value to format.  Where an argument is
-specified by an explicit index, this does not affect the normal
-order for the arguments, even when the explicitly specified index
-would have been the next argument.
-
-So:
-
-    printf "<%*.*s>", $a, $b, $c;
-
-uses C<$a> for the width, C<$b> for the precision, and C<$c>
-as the value to format; while:
-
-  printf "<%*1$.*s>", $a, $b;
-
-would use C<$a> for the width and precision, and C<$b> as the
-value to format.
-
-Here are some more examples; be aware that when using an explicit
-index, the C<$> may need escaping:
-
-  printf "%2\$d %d\n",    12, 34;        # will print "34 12\n"
-  printf "%2\$d %d %d\n", 12, 34;        # will print "34 12 34\n"
-  printf "%3\$d %d %d\n", 12, 34, 56;    # will print "56 12 34\n"
-  printf "%2\$*3\$d %d\n", 12, 34, 3;    # will print " 34 12\n"
-
-=back
-
-If C<use locale> is in effect and POSIX::setlocale() has been called,
-the character used for the decimal separator in formatted floating-point
-numbers is affected by the LC_NUMERIC locale.  See L<perllocale>
-and L<POSIX>.
-
-=item sqrt EXPR
-X<sqrt> X<root> X<square root>
-
-=item sqrt
-
-Return the positive square root of EXPR.  If EXPR is omitted, uses
-C<$_>.  Works only for non-negative operands unless you've
-loaded the C<Math::Complex> module.
-
-    use Math::Complex;
-    print sqrt(-4);    # prints 2i
-
-=item srand EXPR
-X<srand> X<seed> X<randseed>
-
-=item srand
-
-Sets and returns the random number seed for the C<rand> operator.
-
-The point of the function is to "seed" the C<rand> function so that
-C<rand> can produce a different sequence each time you run your
-program.  When called with a parameter, C<srand> uses that for the seed;
-otherwise it (semi-)randomly chooses a seed.  In either case, starting with
-Perl 5.14, it returns the seed.
-
-If C<srand()> is not called explicitly, it is called implicitly without a
-parameter at the first use of the C<rand> operator.  However, this was not true
-of versions of Perl before 5.004, so if your script will run under older
-Perl versions, it should call C<srand>; otherwise most programs won't call
-C<srand()> at all.
-
-But there are a few situations in recent Perls where programs are likely to
-want to call C<srand>.  One is for generating predictable results generally for
-testing or debugging.  There, you use C<srand($seed)>, with the same C<$seed>
-each time.  Another case is that you may want to call C<srand()>
-after a C<fork()> to avoid child processes sharing the same seed value as the
-parent (and consequently each other).
-
-Do B<not> call C<srand()> (i.e., without an argument) more than once per
-process.  The internal state of the random number generator should
-contain more entropy than can be provided by any seed, so calling
-C<srand()> again actually I<loses> randomness.
-
-Most implementations of C<srand> take an integer and will silently
-truncate decimal numbers.  This means C<srand(42)> will usually
-produce the same results as C<srand(42.1)>.  To be safe, always pass
-C<srand> an integer.
-
-In versions of Perl prior to 5.004 the default seed was just the
-current C<time>.  This isn't a particularly good seed, so many old
-programs supply their own seed value (often C<time ^ $$> or C<time ^
-($$ + ($$ << 15))>), but that isn't necessary any more.
-
-Frequently called programs (like CGI scripts) that simply use
-
-    time ^ $$
-
-for a seed can fall prey to the mathematical property that
-
-    a^b == (a+1)^(b+1)
-
-one-third of the time.  So don't do that.
-
-A typical use of the returned seed is for a test program which has too many
-combinations to test comprehensively in the time available to it each run.  It
-can test a random subset each time, and should there be a failure, log the seed
-used for that run so that it can later be used to reproduce the same results.
-
-B<C<rand()> is not cryptographically secure.  You should not rely
-on it in security-sensitive situations.>  As of this writing, a
-number of third-party CPAN modules offer random number generators
-intended by their authors to be cryptographically secure,
-including: L<Data::Entropy>, L<Crypt::Random>, L<Math::Random::Secure>,
-and L<Math::TrulyRandom>.
-
-=item stat FILEHANDLE
-X<stat> X<file, status> X<ctime>
-
-=item stat EXPR
-
-=item stat DIRHANDLE
-
-=item stat
-
-Returns a 13-element list giving the status info for a file, either
-the file opened via FILEHANDLE or DIRHANDLE, or named by EXPR.  If EXPR is 
-omitted, it stats C<$_> (not C<_>!).  Returns the empty list if C<stat> fails.  Typically
-used as follows:
-
-    ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
-       $atime,$mtime,$ctime,$blksize,$blocks)
-           = stat($filename);
-
-Not all fields are supported on all filesystem types.  Here are the
-meanings of the fields:
-
-  0 dev      device number of filesystem
-  1 ino      inode number
-  2 mode     file mode  (type and permissions)
-  3 nlink    number of (hard) links to the file
-  4 uid      numeric user ID of file's owner
-  5 gid      numeric group ID of file's owner
-  6 rdev     the device identifier (special files only)
-  7 size     total size of file, in bytes
-  8 atime    last access time in seconds since the epoch
-  9 mtime    last modify time in seconds since the epoch
- 10 ctime    inode change time in seconds since the epoch (*)
- 11 blksize  preferred block size for file system I/O
- 12 blocks   actual number of blocks allocated
-
-(The epoch was at 00:00 January 1, 1970 GMT.)
-
-(*) Not all fields are supported on all filesystem types. Notably, the
-ctime field is non-portable.  In particular, you cannot expect it to be a
-"creation time"; see L<perlport/"Files and Filesystems"> for details.
-
-If C<stat> is passed the special filehandle consisting of an underline, no
-stat is done, but the current contents of the stat structure from the
-last C<stat>, C<lstat>, or filetest are returned.  Example:
-
-    if (-x $file && (($d) = stat(_)) && $d < 0) {
-        print "$file is executable NFS file\n";
-    }
-
-(This works on machines only for which the device number is negative
-under NFS.)
-
-Because the mode contains both the file type and its permissions, you
-should mask off the file type portion and (s)printf using a C<"%o">
-if you want to see the real permissions.
-
-    $mode = (stat($filename))[2];
-    printf "Permissions are %04o\n", $mode & 07777;
-
-In scalar context, C<stat> returns a boolean value indicating success
-or failure, and, if successful, sets the information associated with
-the special filehandle C<_>.
-
-The L<File::stat> module provides a convenient, by-name access mechanism:
-
-    use File::stat;
-    $sb = stat($filename);
-    printf "File is %s, size is %s, perm %04o, mtime %s\n",
-           $filename, $sb->size, $sb->mode & 07777,
-           scalar localtime $sb->mtime;
-
-You can import symbolic mode constants (C<S_IF*>) and functions
-(C<S_IS*>) from the Fcntl module:
-
-    use Fcntl ':mode';
-
-    $mode = (stat($filename))[2];
-
-    $user_rwx      = ($mode & S_IRWXU) >> 6;
-    $group_read    = ($mode & S_IRGRP) >> 3;
-    $other_execute =  $mode & S_IXOTH;
-
-    printf "Permissions are %04o\n", S_IMODE($mode), "\n";
-
-    $is_setuid     =  $mode & S_ISUID;
-    $is_directory  =  S_ISDIR($mode);
-
-You could write the last two using the C<-u> and C<-d> operators.
-Commonly available C<S_IF*> constants are:
-
-    # Permissions: read, write, execute, for user, group, others.
-
-    S_IRWXU S_IRUSR S_IWUSR S_IXUSR
-    S_IRWXG S_IRGRP S_IWGRP S_IXGRP
-    S_IRWXO S_IROTH S_IWOTH S_IXOTH
-
-    # Setuid/Setgid/Stickiness/SaveText.
-    # Note that the exact meaning of these is system-dependent.
-
-    S_ISUID S_ISGID S_ISVTX S_ISTXT
-
-    # File types.  Not all are necessarily available on
-    # your system.
-
-    S_IFREG S_IFDIR S_IFLNK S_IFBLK S_IFCHR
-    S_IFIFO S_IFSOCK S_IFWHT S_ENFMT
-
-    # The following are compatibility aliases for S_IRUSR,
-    # S_IWUSR, and S_IXUSR.
-
-    S_IREAD S_IWRITE S_IEXEC
-
-and the C<S_IF*> functions are
-
-    S_IMODE($mode)    the part of $mode containing the permission
-                      bits and the setuid/setgid/sticky bits
-
-    S_IFMT($mode)     the part of $mode containing the file type
-                      which can be bit-anded with (for example)
-                      S_IFREG or with the following functions
-
-    # The operators -f, -d, -l, -b, -c, -p, and -S.
-
-    S_ISREG($mode) S_ISDIR($mode) S_ISLNK($mode)
-    S_ISBLK($mode) S_ISCHR($mode) S_ISFIFO($mode) S_ISSOCK($mode)
-
-    # No direct -X operator counterpart, but for the first one
-    # the -g operator is often equivalent.  The ENFMT stands for
-    # record flocking enforcement, a platform-dependent feature.
-
-    S_ISENFMT($mode) S_ISWHT($mode)
-
-See your native chmod(2) and stat(2) documentation for more details
-about the C<S_*> constants.  To get status info for a symbolic link
-instead of the target file behind the link, use the C<lstat> function.
-
-Portability issues: L<perlport/stat>.
-
-=item state EXPR
-X<state>
-
-=item state TYPE EXPR
-
-=item state EXPR : ATTRS
-
-=item state TYPE EXPR : ATTRS
-
-C<state> declares a lexically scoped variable, just like C<my>.
-However, those variables will never be reinitialized, contrary to
-lexical variables that are reinitialized each time their enclosing block
-is entered.
-See L<perlsub/"Persistent Private Variables"> for details.
-
-C<state> variables are enabled only when the C<use feature "state"> pragma 
-is in effect, unless the keyword is written as C<CORE::state>.
-See also L<feature>.
-
-=item study SCALAR
-X<study>
-
-=item study
-
-Takes extra time to study SCALAR (C<$_> if unspecified) in anticipation of
-doing many pattern matches on the string before it is next modified.
-This may or may not save time, depending on the nature and number of
-patterns you are searching and the distribution of character
-frequencies in the string to be searched; you probably want to compare
-run times with and without it to see which is faster.  Those loops
-that scan for many short constant strings (including the constant
-parts of more complex patterns) will benefit most.
-(The way C<study> works is this: a linked list of every
-character in the string to be searched is made, so we know, for
-example, where all the C<'k'> characters are.  From each search string,
-the rarest character is selected, based on some static frequency tables
-constructed from some C programs and English text.  Only those places
-that contain this "rarest" character are examined.)
-
-For example, here is a loop that inserts index producing entries
-before any line containing a certain pattern:
-
-    while (<>) {
-        study;
-        print ".IX foo\n"    if /\bfoo\b/;
-        print ".IX bar\n"    if /\bbar\b/;
-        print ".IX blurfl\n" if /\bblurfl\b/;
-        # ...
-        print;
-    }
-
-In searching for C</\bfoo\b/>, only locations in C<$_> that contain C<f>
-will be looked at, because C<f> is rarer than C<o>.  In general, this is
-a big win except in pathological cases.  The only question is whether
-it saves you more time than it took to build the linked list in the
-first place.
-
-Note that if you have to look for strings that you don't know till
-runtime, you can build an entire loop as a string and C<eval> that to
-avoid recompiling all your patterns all the time.  Together with
-undefining C<$/> to input entire files as one record, this can be quite
-fast, often faster than specialized programs like fgrep(1).  The following
-scans a list of files (C<@files>) for a list of words (C<@words>), and prints
-out the names of those files that contain a match:
-
-    $search = 'while (<>) { study;';
-    foreach $word (@words) {
-        $search .= "++\$seen{\$ARGV} if /\\b$word\\b/;\n";
-    }
-    $search .= "}";
-    @ARGV = @files;
-    undef $/;
-    eval $search;        # this screams
-    $/ = "\n";        # put back to normal input delimiter
-    foreach $file (sort keys(%seen)) {
-        print $file, "\n";
-    }
-
-=item sub NAME BLOCK
-X<sub>
-
-=item sub NAME (PROTO) BLOCK
-
-=item sub NAME : ATTRS BLOCK
-
-=item sub NAME (PROTO) : ATTRS BLOCK
-
-This is subroutine definition, not a real function I<per se>.  Without a
-BLOCK it's just a forward declaration.  Without a NAME, it's an anonymous
-function declaration, so does return a value: the CODE ref of the closure
-just created.
-
-See L<perlsub> and L<perlref> for details about subroutines and
-references; see L<attributes> and L<Attribute::Handlers> for more
-information about attributes.
-
-=item __SUB__
-X<__SUB__>
-
-A special token that returns the a reference to the current subroutine, or
-C<undef> outside of a subroutine.
-
-This token is only available under C<use v5.16> or the "current_sub"
-feature.  See L<feature>.
-
-=item substr EXPR,OFFSET,LENGTH,REPLACEMENT
-X<substr> X<substring> X<mid> X<left> X<right>
-
-=item substr EXPR,OFFSET,LENGTH
-
-=item substr EXPR,OFFSET
-
-Extracts a substring out of EXPR and returns it.  First character is at
-offset zero.  If OFFSET is negative, starts
-that far back from the end of the string.  If LENGTH is omitted, returns
-everything through the end of the string.  If LENGTH is negative, leaves that
-many characters off the end of the string.
-
-    my $s = "The black cat climbed the green tree";
-    my $color  = substr $s, 4, 5;      # black
-    my $middle = substr $s, 4, -11;    # black cat climbed the
-    my $end    = substr $s, 14;        # climbed the green tree
-    my $tail   = substr $s, -4;        # tree
-    my $z      = substr $s, -4, 2;     # tr
-
-You can use the substr() function as an lvalue, in which case EXPR
-must itself be an lvalue.  If you assign something shorter than LENGTH,
-the string will shrink, and if you assign something longer than LENGTH,
-the string will grow to accommodate it.  To keep the string the same
-length, you may need to pad or chop your value using C<sprintf>.
-
-If OFFSET and LENGTH specify a substring that is partly outside the
-string, only the part within the string is returned.  If the substring
-is beyond either end of the string, substr() returns the undefined
-value and produces a warning.  When used as an lvalue, specifying a
-substring that is entirely outside the string raises an exception.
-Here's an example showing the behavior for boundary cases:
-
-    my $name = 'fred';
-    substr($name, 4) = 'dy';         # $name is now 'freddy'
-    my $null = substr $name, 6, 2;   # returns "" (no warning)
-    my $oops = substr $name, 7;      # returns undef, with warning
-    substr($name, 7) = 'gap';        # raises an exception
-
-An alternative to using substr() as an lvalue is to specify the
-replacement string as the 4th argument.  This allows you to replace
-parts of the EXPR and return what was there before in one operation,
-just as you can with splice().
-
-    my $s = "The black cat climbed the green tree";
-    my $z = substr $s, 14, 7, "jumped from";    # climbed
-    # $s is now "The black cat jumped from the green tree"
-
-Note that the lvalue returned by the three-argument version of substr() acts as
-a 'magic bullet'; each time it is assigned to, it remembers which part
-of the original string is being modified; for example:
-
-    $x = '1234';
-    for (substr($x,1,2)) {
-        $_ = 'a';   print $x,"\n";    # prints 1a4
-        $_ = 'xyz'; print $x,"\n";    # prints 1xyz4
-        $x = '56789';
-        $_ = 'pq';  print $x,"\n";    # prints 5pq9
-    }
-
-Prior to Perl version 5.9.1, the result of using an lvalue multiple times was
-unspecified.
-
-=item symlink OLDFILE,NEWFILE
-X<symlink> X<link> X<symbolic link> X<link, symbolic>
-
-Creates a new filename symbolically linked to the old filename.
-Returns C<1> for success, C<0> otherwise.  On systems that don't support
-symbolic links, raises an exception.  To check for that,
-use eval:
-
-    $symlink_exists = eval { symlink("",""); 1 };
-
-Portability issues: L<perlport/symlink>.
-
-=item syscall NUMBER, LIST
-X<syscall> X<system call>
-
-Calls the system call specified as the first element of the list,
-passing the remaining elements as arguments to the system call.  If
-unimplemented, raises an exception.  The arguments are interpreted
-as follows: if a given argument is numeric, the argument is passed as
-an int.  If not, the pointer to the string value is passed.  You are
-responsible to make sure a string is pre-extended long enough to
-receive any result that might be written into a string.  You can't use a
-string literal (or other read-only string) as an argument to C<syscall>
-because Perl has to assume that any string pointer might be written
-through.  If your
-integer arguments are not literals and have never been interpreted in a
-numeric context, you may need to add C<0> to them to force them to look
-like numbers.  This emulates the C<syswrite> function (or vice versa):
-
-    require 'syscall.ph';        # may need to run h2ph
-    $s = "hi there\n";
-    syscall(&SYS_write, fileno(STDOUT), $s, length $s);
-
-Note that Perl supports passing of up to only 14 arguments to your syscall,
-which in practice should (usually) suffice.
-
-Syscall returns whatever value returned by the system call it calls.
-If the system call fails, C<syscall> returns C<-1> and sets C<$!> (errno).
-Note that some system calls I<can> legitimately return C<-1>.  The proper
-way to handle such calls is to assign C<$!=0> before the call, then
-check the value of C<$!> if C<syscall> returns C<-1>.
-
-There's a problem with C<syscall(&SYS_pipe)>: it returns the file
-number of the read end of the pipe it creates, but there is no way
-to retrieve the file number of the other end.  You can avoid this
-problem by using C<pipe> instead.
-
-Portability issues: L<perlport/syscall>.
-
-=item sysopen FILEHANDLE,FILENAME,MODE
-X<sysopen>
-
-=item sysopen FILEHANDLE,FILENAME,MODE,PERMS
-
-Opens the file whose filename is given by FILENAME, and associates it with
-FILEHANDLE.  If FILEHANDLE is an expression, its value is used as the real
-filehandle wanted; an undefined scalar will be suitably autovivified. This
-function calls the underlying operating system's I<open>(2) function with the
-parameters FILENAME, MODE, and PERMS.
-
-The possible values and flag bits of the MODE parameter are
-system-dependent; they are available via the standard module C<Fcntl>.  See
-the documentation of your operating system's I<open>(2) syscall to see
-which values and flag bits are available.  You may combine several flags
-using the C<|>-operator.
-
-Some of the most common values are C<O_RDONLY> for opening the file in
-read-only mode, C<O_WRONLY> for opening the file in write-only mode,
-and C<O_RDWR> for opening the file in read-write mode.
-X<O_RDONLY> X<O_RDWR> X<O_WRONLY>
-
-For historical reasons, some values work on almost every system
-supported by Perl: 0 means read-only, 1 means write-only, and 2
-means read/write.  We know that these values do I<not> work under
-OS/390 & VM/ESA Unix and on the Macintosh; you probably don't want to
-use them in new code.
-
-If the file named by FILENAME does not exist and the C<open> call creates
-it (typically because MODE includes the C<O_CREAT> flag), then the value of
-PERMS specifies the permissions of the newly created file.  If you omit
-the PERMS argument to C<sysopen>, Perl uses the octal value C<0666>.
-These permission values need to be in octal, and are modified by your
-process's current C<umask>.
-X<O_CREAT>
-
-In many systems the C<O_EXCL> flag is available for opening files in
-exclusive mode.  This is B<not> locking: exclusiveness means here that
-if the file already exists, sysopen() fails.  C<O_EXCL> may not work
-on network filesystems, and has no effect unless the C<O_CREAT> flag
-is set as well.  Setting C<O_CREAT|O_EXCL> prevents the file from
-being opened if it is a symbolic link.  It does not protect against
-symbolic links in the file's path.
-X<O_EXCL>
-
-Sometimes you may want to truncate an already-existing file.  This
-can be done using the C<O_TRUNC> flag.  The behavior of
-C<O_TRUNC> with C<O_RDONLY> is undefined.
-X<O_TRUNC>
-
-You should seldom if ever use C<0644> as argument to C<sysopen>, because
-that takes away the user's option to have a more permissive umask.
-Better to omit it.  See the perlfunc(1) entry on C<umask> for more
-on this.
-
-Note that C<sysopen> depends on the fdopen() C library function.
-On many Unix systems, fdopen() is known to fail when file descriptors
-exceed a certain value, typically 255. If you need more file
-descriptors than that, consider rebuilding Perl to use the C<sfio>
-library, or perhaps using the POSIX::open() function.
-
-See L<perlopentut> for a kinder, gentler explanation of opening files.
-
-Portability issues: L<perlport/sysopen>.
-
-=item sysread FILEHANDLE,SCALAR,LENGTH,OFFSET
-X<sysread>
-
-=item sysread FILEHANDLE,SCALAR,LENGTH
-
-Attempts to read LENGTH bytes of data into variable SCALAR from the
-specified FILEHANDLE, using the read(2).  It bypasses
-buffered IO, so mixing this with other kinds of reads, C<print>,
-C<write>, C<seek>, C<tell>, or C<eof> can cause confusion because the
-perlio or stdio layers usually buffers data.  Returns the number of
-bytes actually read, C<0> at end of file, or undef if there was an
-error (in the latter case C<$!> is also set).  SCALAR will be grown or
-shrunk so that the last byte actually read is the last byte of the
-scalar after the read.
-
-An OFFSET may be specified to place the read data at some place in the
-string other than the beginning.  A negative OFFSET specifies
-placement at that many characters counting backwards from the end of
-the string.  A positive OFFSET greater than the length of SCALAR
-results in the string being padded to the required size with C<"\0">
-bytes before the result of the read is appended.
-
-There is no syseof() function, which is ok, since eof() doesn't work
-well on device files (like ttys) anyway.  Use sysread() and check
-for a return value for 0 to decide whether you're done.
-
-Note that if the filehandle has been marked as C<:utf8> Unicode
-characters are read instead of bytes (the LENGTH, OFFSET, and the
-return value of sysread() are in Unicode characters).
-The C<:encoding(...)> layer implicitly introduces the C<:utf8> layer.
-See L</binmode>, L</open>, and the C<open> pragma, L<open>.
-
-=item sysseek FILEHANDLE,POSITION,WHENCE
-X<sysseek> X<lseek>
-
-Sets FILEHANDLE's system position in bytes using lseek(2).  FILEHANDLE may
-be an expression whose value gives the name of the filehandle.  The values
-for WHENCE are C<0> to set the new position to POSITION; C<1> to set the it
-to the current position plus POSITION; and C<2> to set it to EOF plus
-POSITION, typically negative.
-
-Note the I<in bytes>: even if the filehandle has been set to operate
-on characters (for example by using the C<:encoding(utf8)> I/O layer),
-tell() will return byte offsets, not character offsets (because
-implementing that would render sysseek() unacceptably slow).
-
-sysseek() bypasses normal buffered IO, so mixing it with reads other
-than C<sysread> (for example C<< <> >> or read()) C<print>, C<write>,
-C<seek>, C<tell>, or C<eof> may cause confusion.
-
-For WHENCE, you may also use the constants C<SEEK_SET>, C<SEEK_CUR>,
-and C<SEEK_END> (start of the file, current position, end of the file)
-from the Fcntl module.  Use of the constants is also more portable
-than relying on 0, 1, and 2.  For example to define a "systell" function:
-
-    use Fcntl 'SEEK_CUR';
-    sub systell { sysseek($_[0], 0, SEEK_CUR) }
-
-Returns the new position, or the undefined value on failure.  A position
-of zero is returned as the string C<"0 but true">; thus C<sysseek> returns
-true on success and false on failure, yet you can still easily determine
-the new position.
-
-=item system LIST
-X<system> X<shell>
-
-=item system PROGRAM LIST
-
-Does exactly the same thing as C<exec LIST>, except that a fork is
-done first and the parent process waits for the child process to
-exit.  Note that argument processing varies depending on the
-number of arguments.  If there is more than one argument in LIST,
-or if LIST is an array with more than one value, starts the program
-given by the first element of the list with arguments given by the
-rest of the list.  If there is only one scalar argument, the argument
-is checked for shell metacharacters, and if there are any, the
-entire argument is passed to the system's command shell for parsing
-(this is C</bin/sh -c> on Unix platforms, but varies on other
-platforms).  If there are no shell metacharacters in the argument,
-it is split into words and passed directly to C<execvp>, which is
-more efficient.
-
-Beginning with v5.6.0, Perl will attempt to flush all files opened for
-output before any operation that may do a fork, but this may not be
-supported on some platforms (see L<perlport>).  To be safe, you may need
-to set C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method
-of C<IO::Handle> on any open handles.
-
-The return value is the exit status of the program as returned by the
-C<wait> call.  To get the actual exit value, shift right by eight (see
-below). See also L</exec>.  This is I<not> what you want to use to capture
-the output from a command; for that you should use merely backticks or
-C<qx//>, as described in L<perlop/"`STRING`">.  Return value of -1
-indicates a failure to start the program or an error of the wait(2) system
-call (inspect $! for the reason).
-
-If you'd like to make C<system> (and many other bits of Perl) die on error,
-have a look at the L<autodie> pragma.
-
-Like C<exec>, C<system> allows you to lie to a program about its name if
-you use the C<system PROGRAM LIST> syntax.  Again, see L</exec>.
-
-Since C<SIGINT> and C<SIGQUIT> are ignored during the execution of
-C<system>, if you expect your program to terminate on receipt of these
-signals you will need to arrange to do so yourself based on the return
-value.
-
-    @args = ("command", "arg1", "arg2");
-    system(@args) == 0
-        or die "system @args failed: $?"
-
-If you'd like to manually inspect C<system>'s failure, you can check all
-possible failure modes by inspecting C<$?> like this:
-
-    if ($? == -1) {
-        print "failed to execute: $!\n";
-    }
-    elsif ($? & 127) {
-        printf "child died with signal %d, %s coredump\n",
-            ($? & 127),  ($? & 128) ? 'with' : 'without';
-    }
-    else {
-        printf "child exited with value %d\n", $? >> 8;
-    }
-
-Alternatively, you may inspect the value of C<${^CHILD_ERROR_NATIVE}>
-with the C<W*()> calls from the POSIX module.
-
-When C<system>'s arguments are executed indirectly by the shell, 
-results and return codes are subject to its quirks.
-See L<perlop/"`STRING`"> and L</exec> for details.
-
-Since C<system> does a C<fork> and C<wait> it may affect a C<SIGCHLD>
-handler. See L<perlipc> for details.
-
-Portability issues: L<perlport/system>.
-
-=item syswrite FILEHANDLE,SCALAR,LENGTH,OFFSET
-X<syswrite>
-
-=item syswrite FILEHANDLE,SCALAR,LENGTH
-
-=item syswrite FILEHANDLE,SCALAR
-
-Attempts to write LENGTH bytes of data from variable SCALAR to the
-specified FILEHANDLE, using write(2).  If LENGTH is
-not specified, writes whole SCALAR.  It bypasses buffered IO, so
-mixing this with reads (other than C<sysread())>, C<print>, C<write>,
-C<seek>, C<tell>, or C<eof> may cause confusion because the perlio and
-stdio layers usually buffer data.  Returns the number of bytes
-actually written, or C<undef> if there was an error (in this case the
-errno variable C<$!> is also set).  If the LENGTH is greater than the
-data available in the SCALAR after the OFFSET, only as much data as is
-available will be written.
-
-An OFFSET may be specified to write the data from some part of the
-string other than the beginning.  A negative OFFSET specifies writing
-that many characters counting backwards from the end of the string.
-If SCALAR is of length zero, you can only use an OFFSET of 0.
-
-B<WARNING>: If the filehandle is marked C<:utf8>, Unicode characters
-encoded in UTF-8 are written instead of bytes, and the LENGTH, OFFSET, and
-return value of syswrite() are in (UTF8-encoded Unicode) characters.
-The C<:encoding(...)> layer implicitly introduces the C<:utf8> layer.
-Alternately, if the handle is not marked with an encoding but you
-attempt to write characters with code points over 255, raises an exception.
-See L</binmode>, L</open>, and the C<open> pragma, L<open>.
-
-=item tell FILEHANDLE
-X<tell>
-
-=item tell
-
-Returns the current position I<in bytes> for FILEHANDLE, or -1 on
-error.  FILEHANDLE may be an expression whose value gives the name of
-the actual filehandle.  If FILEHANDLE is omitted, assumes the file
-last read.
-
-Note the I<in bytes>: even if the filehandle has been set to
-operate on characters (for example by using the C<:encoding(utf8)> open
-layer), tell() will return byte offsets, not character offsets (because
-that would render seek() and tell() rather slow).
-
-The return value of tell() for the standard streams like the STDIN
-depends on the operating system: it may return -1 or something else.
-tell() on pipes, fifos, and sockets usually returns -1.
-
-There is no C<systell> function.  Use C<sysseek(FH, 0, 1)> for that.
-
-Do not use tell() (or other buffered I/O operations) on a filehandle
-that has been manipulated by sysread(), syswrite(), or sysseek().
-Those functions ignore the buffering, while tell() does not.
-
-=item telldir DIRHANDLE
-X<telldir>
-
-Returns the current position of the C<readdir> routines on DIRHANDLE.
-Value may be given to C<seekdir> to access a particular location in a
-directory.  C<telldir> has the same caveats about possible directory
-compaction as the corresponding system library routine.
-
-=item tie VARIABLE,CLASSNAME,LIST
-X<tie>
-
-This function binds a variable to a package class that will provide the
-implementation for the variable.  VARIABLE is the name of the variable
-to be enchanted.  CLASSNAME is the name of a class implementing objects
-of correct type.  Any additional arguments are passed to the C<new>
-method of the class (meaning C<TIESCALAR>, C<TIEHANDLE>, C<TIEARRAY>,
-or C<TIEHASH>).  Typically these are arguments such as might be passed
-to the C<dbm_open()> function of C.  The object returned by the C<new>
-method is also returned by the C<tie> function, which would be useful
-if you want to access other methods in CLASSNAME.
-
-Note that functions such as C<keys> and C<values> may return huge lists
-when used on large objects, like DBM files.  You may prefer to use the
-C<each> function to iterate over such.  Example:
-
-    # print out history file offsets
-    use NDBM_File;
-    tie(%HIST, 'NDBM_File', '/usr/lib/news/history', 1, 0);
-    while (($key,$val) = each %HIST) {
-        print $key, ' = ', unpack('L',$val), "\n";
-    }
-    untie(%HIST);
-
-A class implementing a hash should have the following methods:
-
-    TIEHASH classname, LIST
-    FETCH this, key
-    STORE this, key, value
-    DELETE this, key
-    CLEAR this
-    EXISTS this, key
-    FIRSTKEY this
-    NEXTKEY this, lastkey
-    SCALAR this
-    DESTROY this
-    UNTIE this
-
-A class implementing an ordinary array should have the following methods:
-
-    TIEARRAY classname, LIST
-    FETCH this, key
-    STORE this, key, value
-    FETCHSIZE this
-    STORESIZE this, count
-    CLEAR this
-    PUSH this, LIST
-    POP this
-    SHIFT this
-    UNSHIFT this, LIST
-    SPLICE this, offset, length, LIST
-    EXTEND this, count
-    DESTROY this
-    UNTIE this
-
-A class implementing a filehandle should have the following methods:
-
-    TIEHANDLE classname, LIST
-    READ this, scalar, length, offset
-    READLINE this
-    GETC this
-    WRITE this, scalar, length, offset
-    PRINT this, LIST
-    PRINTF this, format, LIST
-    BINMODE this
-    EOF this
-    FILENO this
-    SEEK this, position, whence
-    TELL this
-    OPEN this, mode, LIST
-    CLOSE this
-    DESTROY this
-    UNTIE this
-
-A class implementing a scalar should have the following methods:
-
-    TIESCALAR classname, LIST
-    FETCH this,
-    STORE this, value
-    DESTROY this
-    UNTIE this
-
-Not all methods indicated above need be implemented.  See L<perltie>,
-L<Tie::Hash>, L<Tie::Array>, L<Tie::Scalar>, and L<Tie::Handle>.
-
-Unlike C<dbmopen>, the C<tie> function will not C<use> or C<require> a module
-for you; you need to do that explicitly yourself.  See L<DB_File>
-or the F<Config> module for interesting C<tie> implementations.
-
-For further details see L<perltie>, L<"tied VARIABLE">.
-
-=item tied VARIABLE
-X<tied>
-
-Returns a reference to the object underlying VARIABLE (the same value
-that was originally returned by the C<tie> call that bound the variable
-to a package.)  Returns the undefined value if VARIABLE isn't tied to a
-package.
-
-=item time
-X<time> X<epoch>
-
-Returns the number of non-leap seconds since whatever time the system
-considers to be the epoch, suitable for feeding to C<gmtime> and
-C<localtime>. On most systems the epoch is 00:00:00 UTC, January 1, 1970;
-a prominent exception being Mac OS Classic which uses 00:00:00, January 1,
-1904 in the current local time zone for its epoch.
-
-For measuring time in better granularity than one second, use the
-L<Time::HiRes> module from Perl 5.8 onwards (or from CPAN before then), or,
-if you have gettimeofday(2), you may be able to use the C<syscall>
-interface of Perl.  See L<perlfaq8> for details.
-
-For date and time processing look at the many related modules on CPAN.
-For a comprehensive date and time representation look at the
-L<DateTime> module.
-
-=item times
-X<times>
-
-Returns a four-element list giving the user and system times in
-seconds for this process and any exited children of this process.
-
-    ($user,$system,$cuser,$csystem) = times;
-
-In scalar context, C<times> returns C<$user>.
-
-Children's times are only included for terminated children.
-
-Portability issues: L<perlport/times>.
-
-=item tr///
-
-The transliteration operator.  Same as C<y///>.  See
-L<perlop/"Quote and Quote-like Operators">.
-
-=item truncate FILEHANDLE,LENGTH
-X<truncate>
-
-=item truncate EXPR,LENGTH
-
-Truncates the file opened on FILEHANDLE, or named by EXPR, to the
-specified length.  Raises an exception if truncate isn't implemented
-on your system.  Returns true if successful, C<undef> on error.
-
-The behavior is undefined if LENGTH is greater than the length of the
-file.
-
-The position in the file of FILEHANDLE is left unchanged.  You may want to
-call L<seek|/"seek FILEHANDLE,POSITION,WHENCE"> before writing to the file.
-
-Portability issues: L<perlport/truncate>.
-
-=item uc EXPR
-X<uc> X<uppercase> X<toupper>
-
-=item uc
-
-Returns an uppercased version of EXPR.  This is the internal function
-implementing the C<\U> escape in double-quoted strings.
-It does not attempt to do titlecase mapping on initial letters.  See
-L</ucfirst> for that.
-
-If EXPR is omitted, uses C<$_>.
-
-This function behaves the same way under various pragma, such as in a locale,
-as L</lc> does.
-
-=item ucfirst EXPR
-X<ucfirst> X<uppercase>
-
-=item ucfirst
-
-Returns the value of EXPR with the first character in uppercase
-(titlecase in Unicode).  This is the internal function implementing
-the C<\u> escape in double-quoted strings.
-
-If EXPR is omitted, uses C<$_>.
-
-This function behaves the same way under various pragma, such as in a locale,
-as L</lc> does.
-
-=item umask EXPR
-X<umask>
-
-=item umask
-
-Sets the umask for the process to EXPR and returns the previous value.
-If EXPR is omitted, merely returns the current umask.
-
-The Unix permission C<rwxr-x---> is represented as three sets of three
-bits, or three octal digits: C<0750> (the leading 0 indicates octal
-and isn't one of the digits).  The C<umask> value is such a number
-representing disabled permissions bits.  The permission (or "mode")
-values you pass C<mkdir> or C<sysopen> are modified by your umask, so
-even if you tell C<sysopen> to create a file with permissions C<0777>,
-if your umask is C<0022>, then the file will actually be created with
-permissions C<0755>.  If your C<umask> were C<0027> (group can't
-write; others can't read, write, or execute), then passing
-C<sysopen> C<0666> would create a file with mode C<0640> (because 
-C<0666 &~ 027> is C<0640>).
-
-Here's some advice: supply a creation mode of C<0666> for regular
-files (in C<sysopen>) and one of C<0777> for directories (in
-C<mkdir>) and executable files.  This gives users the freedom of
-choice: if they want protected files, they might choose process umasks
-of C<022>, C<027>, or even the particularly antisocial mask of C<077>.
-Programs should rarely if ever make policy decisions better left to
-the user.  The exception to this is when writing files that should be
-kept private: mail files, web browser cookies, I<.rhosts> files, and
-so on.
-
-If umask(2) is not implemented on your system and you are trying to
-restrict access for I<yourself> (i.e., C<< (EXPR & 0700) > 0 >>), 
-raises an exception.  If umask(2) is not implemented and you are
-not trying to restrict access for yourself, returns C<undef>.
-
-Remember that a umask is a number, usually given in octal; it is I<not> a
-string of octal digits.  See also L</oct>, if all you have is a string.
-
-Portability issues: L<perlport/umask>.
-
-=item undef EXPR
-X<undef> X<undefine>
-
-=item undef
-
-Undefines the value of EXPR, which must be an lvalue.  Use only on a
-scalar value, an array (using C<@>), a hash (using C<%>), a subroutine
-(using C<&>), or a typeglob (using C<*>).  Saying C<undef $hash{$key}>
-will probably not do what you expect on most predefined variables or
-DBM list values, so don't do that; see L</delete>.  Always returns the
-undefined value.  You can omit the EXPR, in which case nothing is
-undefined, but you still get an undefined value that you could, for
-instance, return from a subroutine, assign to a variable, or pass as a
-parameter.  Examples:
-
-    undef $foo;
-    undef $bar{'blurfl'};      # Compare to: delete $bar{'blurfl'};
-    undef @ary;
-    undef %hash;
-    undef &mysub;
-    undef *xyz;       # destroys $xyz, @xyz, %xyz, &xyz, etc.
-    return (wantarray ? (undef, $errmsg) : undef) if $they_blew_it;
-    select undef, undef, undef, 0.25;
-    ($a, $b, undef, $c) = &foo;       # Ignore third value returned
-
-Note that this is a unary operator, not a list operator.
-
-=item unlink LIST
-X<unlink> X<delete> X<remove> X<rm> X<del>
-
-=item unlink
-
-Deletes a list of files. On success, it returns the number of files
-it successfully deleted. On failure, it returns false and sets C<$!>
-(errno):
-
-    my $unlinked = unlink 'a', 'b', 'c';
-    unlink @goners;
-    unlink glob "*.bak";
-
-On error, C<unlink> will not tell you which files it could not remove.
-If you want to know which files you could not remove, try them one
-at a time:
-
-     foreach my $file ( @goners ) {
-         unlink $file or warn "Could not unlink $file: $!";
-     }
-
-Note: C<unlink> will not attempt to delete directories unless you are
-superuser and the B<-U> flag is supplied to Perl. Even if these
-conditions are met, be warned that unlinking a directory can inflict
-damage on your filesystem.  Finally, using C<unlink> on directories is
-not supported on many operating systems.  Use C<rmdir> instead.
-
-If LIST is omitted, C<unlink> uses C<$_>.
-
-=item unpack TEMPLATE,EXPR
-X<unpack>
-
-=item unpack TEMPLATE
-
-C<unpack> does the reverse of C<pack>: it takes a string
-and expands it out into a list of values.
-(In scalar context, it returns merely the first value produced.)
-
-If EXPR is omitted, unpacks the C<$_> string.
-See L<perlpacktut> for an introduction to this function.
-
-The string is broken into chunks described by the TEMPLATE.  Each chunk
-is converted separately to a value.  Typically, either the string is a result
-of C<pack>, or the characters of the string represent a C structure of some
-kind.
-
-The TEMPLATE has the same format as in the C<pack> function.
-Here's a subroutine that does substring:
-
-    sub substr {
-        my($what,$where,$howmuch) = @_;
-        unpack("x$where a$howmuch", $what);
-    }
-
-and then there's
-
-    sub ordinal { unpack("W",$_[0]); } # same as ord()
-
-In addition to fields allowed in pack(), you may prefix a field with
-a %<number> to indicate that
-you want a <number>-bit checksum of the items instead of the items
-themselves.  Default is a 16-bit checksum.  Checksum is calculated by
-summing numeric values of expanded values (for string fields the sum of
-C<ord($char)> is taken; for bit fields the sum of zeroes and ones).
-
-For example, the following
-computes the same number as the System V sum program:
-
-    $checksum = do {
-        local $/;  # slurp!
-        unpack("%32W*",<>) % 65535;
-    };
-
-The following efficiently counts the number of set bits in a bit vector:
-
-    $setbits = unpack("%32b*", $selectmask);
-
-The C<p> and C<P> formats should be used with care.  Since Perl
-has no way of checking whether the value passed to C<unpack()>
-corresponds to a valid memory location, passing a pointer value that's
-not known to be valid is likely to have disastrous consequences.
-
-If there are more pack codes or if the repeat count of a field or a group
-is larger than what the remainder of the input string allows, the result
-is not well defined: the repeat count may be decreased, or
-C<unpack()> may produce empty strings or zeros, or it may raise an exception.
-If the input string is longer than one described by the TEMPLATE,
-the remainder of that input string is ignored.
-
-See L</pack> for more examples and notes.
-
-=item untie VARIABLE
-X<untie>
-
-Breaks the binding between a variable and a package.
-(See L<tie|/tie VARIABLE,CLASSNAME,LIST>.)
-Has no effect if the variable is not tied.
-
-=item unshift ARRAY,LIST
-X<unshift>
-
-=item unshift EXPR,LIST
-
-Does the opposite of a C<shift>.  Or the opposite of a C<push>,
-depending on how you look at it.  Prepends list to the front of the
-array and returns the new number of elements in the array.
-
-    unshift(@ARGV, '-e') unless $ARGV[0] =~ /^-/;
-
-Note the LIST is prepended whole, not one element at a time, so the
-prepended elements stay in the same order.  Use C<reverse> to do the
-reverse.
-
-Starting with Perl 5.14, C<unshift> can take a scalar EXPR, which must hold
-a reference to an unblessed array.  The argument will be dereferenced
-automatically.  This aspect of C<unshift> is considered highly
-experimental.  The exact behaviour may change in a future version of Perl.
-
-=item use Module VERSION LIST
-X<use> X<module> X<import>
-
-=item use Module VERSION
-
-=item use Module LIST
-
-=item use Module
-
-=item use VERSION
-
-Imports some semantics into the current package from the named module,
-generally by aliasing certain subroutine or variable names into your
-package.  It is exactly equivalent to
-
-    BEGIN { require Module; Module->import( LIST ); }
-
-except that Module I<must> be a bareword.
-The importation can be made conditional; see L<if>.
-
-In the peculiar C<use VERSION> form, VERSION may be either a positive
-decimal fraction such as 5.006, which will be compared to C<$]>, or a v-string
-of the form v5.6.1, which will be compared to C<$^V> (aka $PERL_VERSION).  An
-exception is raised if VERSION is greater than the version of the
-current Perl interpreter; Perl will not attempt to parse the rest of the
-file.  Compare with L</require>, which can do a similar check at run time.
-Symmetrically, C<no VERSION> allows you to specify that you want a version
-of Perl older than the specified one.
-
-Specifying VERSION as a literal of the form v5.6.1 should generally be
-avoided, because it leads to misleading error messages under earlier
-versions of Perl (that is, prior to 5.6.0) that do not support this
-syntax.  The equivalent numeric version should be used instead.
-
-    use v5.6.1;     # compile time version check
-    use 5.6.1;      # ditto
-    use 5.006_001;  # ditto; preferred for backwards compatibility
-
-This is often useful if you need to check the current Perl version before
-C<use>ing library modules that won't work with older versions of Perl.
-(We try not to do this more than we have to.)
-
-Also, if the specified Perl version is greater than or equal to 5.9.5,
-C<use VERSION> will also load the C<feature> pragma and enable all
-features available in the requested version.  See L<feature>.
-Similarly, if the specified Perl version is greater than or equal to
-5.11.0, strictures are enabled lexically as with C<use strict> (except
-that the F<strict.pm> file is not actually loaded).
-
-The C<BEGIN> forces the C<require> and C<import> to happen at compile time.  The
-C<require> makes sure the module is loaded into memory if it hasn't been
-yet.  The C<import> is not a builtin; it's just an ordinary static method
-call into the C<Module> package to tell the module to import the list of
-features back into the current package.  The module can implement its
-C<import> method any way it likes, though most modules just choose to
-derive their C<import> method via inheritance from the C<Exporter> class that
-is defined in the C<Exporter> module.  See L<Exporter>.  If no C<import>
-method can be found then the call is skipped, even if there is an AUTOLOAD
-method.
-
-If you do not want to call the package's C<import> method (for instance,
-to stop your namespace from being altered), explicitly supply the empty list:
-
-    use Module ();
-
-That is exactly equivalent to
-
-    BEGIN { require Module }
-
-If the VERSION argument is present between Module and LIST, then the
-C<use> will call the VERSION method in class Module with the given
-version as an argument.  The default VERSION method, inherited from
-the UNIVERSAL class, croaks if the given version is larger than the
-value of the variable C<$Module::VERSION>.
-
-Again, there is a distinction between omitting LIST (C<import> called
-with no arguments) and an explicit empty LIST C<()> (C<import> not
-called).  Note that there is no comma after VERSION!
-
-Because this is a wide-open interface, pragmas (compiler directives)
-are also implemented this way.  Currently implemented pragmas are:
-
-    use constant;
-    use diagnostics;
-    use integer;
-    use sigtrap  qw(SEGV BUS);
-    use strict   qw(subs vars refs);
-    use subs     qw(afunc blurfl);
-    use warnings qw(all);
-    use sort     qw(stable _quicksort _mergesort);
-
-Some of these pseudo-modules import semantics into the current
-block scope (like C<strict> or C<integer>, unlike ordinary modules,
-which import symbols into the current package (which are effective
-through the end of the file).
-
-Because C<use> takes effect at compile time, it doesn't respect the
-ordinary flow control of the code being compiled.  In particular, putting
-a C<use> inside the false branch of a conditional doesn't prevent it
-from being processed.  If a module or pragma only needs to be loaded 
-conditionally, this can be done using the L<if> pragma:
-
-    use if $] < 5.008, "utf8";
-    use if WANT_WARNINGS, warnings => qw(all);
-
-There's a corresponding C<no> declaration that unimports meanings imported
-by C<use>, i.e., it calls C<unimport Module LIST> instead of C<import>.
-It behaves just as C<import> does with VERSION, an omitted or empty LIST, 
-or no unimport method being found.
-
-    no integer;
-    no strict 'refs';
-    no warnings;
-
-Care should be taken when using the C<no VERSION> form of C<no>.  It is
-I<only> meant to be used to assert that the running Perl is of a earlier
-version than its argument and I<not> to undo the feature-enabling side effects
-of C<use VERSION>.
-
-See L<perlmodlib> for a list of standard modules and pragmas.  See L<perlrun>
-for the C<-M> and C<-m> command-line options to Perl that give C<use>
-functionality from the command-line.
-
-=item utime LIST
-X<utime>
-
-Changes the access and modification times on each file of a list of
-files.  The first two elements of the list must be the NUMERIC access
-and modification times, in that order.  Returns the number of files
-successfully changed.  The inode change time of each file is set
-to the current time.  For example, this code has the same effect as the
-Unix touch(1) command when the files I<already exist> and belong to
-the user running the program:
-
-    #!/usr/bin/perl
-    $atime = $mtime = time;
-    utime $atime, $mtime, @ARGV;
-
-Since Perl 5.7.2, if the first two elements of the list are C<undef>, 
-the utime(2) syscall from your C library is called with a null second
-argument. On most systems, this will set the file's access and
-modification times to the current time (i.e., equivalent to the example
-above) and will work even on files you don't own provided you have write
-permission:
-
-    for $file (@ARGV) {
-	utime(undef, undef, $file) 
-	    || warn "couldn't touch $file: $!";
-    } 
-
-Under NFS this will use the time of the NFS server, not the time of
-the local machine.  If there is a time synchronization problem, the
-NFS server and local machine will have different times.  The Unix
-touch(1) command will in fact normally use this form instead of the
-one shown in the first example.
-
-Passing only one of the first two elements as C<undef> is
-equivalent to passing a 0 and will not have the effect 
-described when both are C<undef>.  This also triggers an
-uninitialized warning.
-
-On systems that support futimes(2), you may pass filehandles among the
-files.  On systems that don't support futimes(2), passing filehandles raises
-an exception.  Filehandles must be passed as globs or glob references to be
-recognized; barewords are considered filenames.
-
-Portability issues: L<perlport/utime>.
-
-=item values HASH
-X<values>
-
-=item values ARRAY
-
-=item values EXPR
-
-Returns a list consisting of all the values of the named hash, or the values
-of an array. (In scalar context, returns the number of values.)
-
-The values are returned in an apparently random order.  The actual
-random order is subject to change in future versions of Perl, but it
-is guaranteed to be the same order as either the C<keys> or C<each>
-function would produce on the same (unmodified) hash.  Since Perl
-5.8.1 the ordering is different even between different runs of Perl
-for security reasons (see L<perlsec/"Algorithmic Complexity Attacks">).
-
-As a side effect, calling values() resets the HASH or ARRAY's internal
-iterator;
-see L</each>. (In particular, calling values() in void context resets
-the iterator with no other overhead. Apart from resetting the iterator,
-C<values @array> in list context is the same as plain C<@array>.
-We recommend that you use void context C<keys @array> for this, but reasoned
-that it taking C<values @array> out would require more documentation than
-leaving it in.)
-
-Note that the values are not copied, which means modifying them will
-modify the contents of the hash:
-
-    for (values %hash)      { s/foo/bar/g }   # modifies %hash values
-    for (@hash{keys %hash}) { s/foo/bar/g }   # same
-
-Starting with Perl 5.14, C<values> can take a scalar EXPR, which must hold
-a reference to an unblessed hash or array.  The argument will be
-dereferenced automatically.  This aspect of C<values> is considered highly
-experimental.  The exact behaviour may change in a future version of Perl.
-
-    for (values $hashref) { ... }
-    for (values $obj->get_arrayref) { ... }
-
-See also C<keys>, C<each>, and C<sort>.
-
-=item vec EXPR,OFFSET,BITS
-X<vec> X<bit> X<bit vector>
-
-Treats the string in EXPR as a bit vector made up of elements of
-width BITS and returns the value of the element specified by OFFSET
-as an unsigned integer.  BITS therefore specifies the number of bits
-that are reserved for each element in the bit vector.  This must
-be a power of two from 1 to 32 (or 64, if your platform supports
-that).
-
-If BITS is 8, "elements" coincide with bytes of the input string.
-
-If BITS is 16 or more, bytes of the input string are grouped into chunks
-of size BITS/8, and each group is converted to a number as with
-pack()/unpack() with big-endian formats C<n>/C<N> (and analogously
-for BITS==64).  See L<"pack"> for details.
-
-If bits is 4 or less, the string is broken into bytes, then the bits
-of each byte are broken into 8/BITS groups.  Bits of a byte are
-numbered in a little-endian-ish way, as in C<0x01>, C<0x02>,
-C<0x04>, C<0x08>, C<0x10>, C<0x20>, C<0x40>, C<0x80>.  For example,
-breaking the single input byte C<chr(0x36)> into two groups gives a list
-C<(0x6, 0x3)>; breaking it into 4 groups gives C<(0x2, 0x1, 0x3, 0x0)>.
-
-C<vec> may also be assigned to, in which case parentheses are needed
-to give the expression the correct precedence as in
-
-    vec($image, $max_x * $x + $y, 8) = 3;
-
-If the selected element is outside the string, the value 0 is returned.
-If an element off the end of the string is written to, Perl will first
-extend the string with sufficiently many zero bytes.   It is an error
-to try to write off the beginning of the string (i.e., negative OFFSET).
-
-If the string happens to be encoded as UTF-8 internally (and thus has
-the UTF8 flag set), this is ignored by C<vec>, and it operates on the
-internal byte string, not the conceptual character string, even if you
-only have characters with values less than 256. 
-
-Strings created with C<vec> can also be manipulated with the logical
-operators C<|>, C<&>, C<^>, and C<~>.  These operators will assume a bit
-vector operation is desired when both operands are strings.
-See L<perlop/"Bitwise String Operators">.
-
-The following code will build up an ASCII string saying C<'PerlPerlPerl'>.
-The comments show the string after each step.  Note that this code works
-in the same way on big-endian or little-endian machines.
-
-    my $foo = '';
-    vec($foo,  0, 32) = 0x5065726C; # 'Perl'
-
-    # $foo eq "Perl" eq "\x50\x65\x72\x6C", 32 bits
-    print vec($foo, 0, 8);  # prints 80 == 0x50 == ord('P')
-
-    vec($foo,  2, 16) = 0x5065; # 'PerlPe'
-    vec($foo,  3, 16) = 0x726C; # 'PerlPerl'
-    vec($foo,  8,  8) = 0x50;   # 'PerlPerlP'
-    vec($foo,  9,  8) = 0x65;   # 'PerlPerlPe'
-    vec($foo, 20,  4) = 2;      # 'PerlPerlPe'   . "\x02"
-    vec($foo, 21,  4) = 7;      # 'PerlPerlPer'
-                                   # 'r' is "\x72"
-    vec($foo, 45,  2) = 3;      # 'PerlPerlPer'  . "\x0c"
-    vec($foo, 93,  1) = 1;      # 'PerlPerlPer'  . "\x2c"
-    vec($foo, 94,  1) = 1;      # 'PerlPerlPerl'
-                                   # 'l' is "\x6c"
-
-To transform a bit vector into a string or list of 0's and 1's, use these:
-
-    $bits = unpack("b*", $vector);
-    @bits = split(//, unpack("b*", $vector));
-
-If you know the exact length in bits, it can be used in place of the C<*>.
-
-Here is an example to illustrate how the bits actually fall in place:
-
-    #!/usr/bin/perl -wl
-
-    print <<'EOT';
-                                      0         1         2         3
-                       unpack("V",$_) 01234567890123456789012345678901
-    ------------------------------------------------------------------
-    EOT
-
-    for $w (0..3) {
-        $width = 2**$w;
-        for ($shift=0; $shift < $width; ++$shift) {
-            for ($off=0; $off < 32/$width; ++$off) {
-                $str = pack("B*", "0"x32);
-                $bits = (1<<$shift);
-                vec($str, $off, $width) = $bits;
-                $res = unpack("b*",$str);
-                $val = unpack("V", $str);
-                write;
-            }
-        }
-    }
-
-    format STDOUT =
-    vec($_,@#,@#) = @<< == @######### @>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-    $off, $width, $bits, $val, $res
-    .
-    __END__
-
-Regardless of the machine architecture on which it runs, the 
-example above should print the following table:
-
-                                      0         1         2         3
-                       unpack("V",$_) 01234567890123456789012345678901
-    ------------------------------------------------------------------
-    vec($_, 0, 1) = 1   ==          1 10000000000000000000000000000000
-    vec($_, 1, 1) = 1   ==          2 01000000000000000000000000000000
-    vec($_, 2, 1) = 1   ==          4 00100000000000000000000000000000
-    vec($_, 3, 1) = 1   ==          8 00010000000000000000000000000000
-    vec($_, 4, 1) = 1   ==         16 00001000000000000000000000000000
-    vec($_, 5, 1) = 1   ==         32 00000100000000000000000000000000
-    vec($_, 6, 1) = 1   ==         64 00000010000000000000000000000000
-    vec($_, 7, 1) = 1   ==        128 00000001000000000000000000000000
-    vec($_, 8, 1) = 1   ==        256 00000000100000000000000000000000
-    vec($_, 9, 1) = 1   ==        512 00000000010000000000000000000000
-    vec($_,10, 1) = 1   ==       1024 00000000001000000000000000000000
-    vec($_,11, 1) = 1   ==       2048 00000000000100000000000000000000
-    vec($_,12, 1) = 1   ==       4096 00000000000010000000000000000000
-    vec($_,13, 1) = 1   ==       8192 00000000000001000000000000000000
-    vec($_,14, 1) = 1   ==      16384 00000000000000100000000000000000
-    vec($_,15, 1) = 1   ==      32768 00000000000000010000000000000000
-    vec($_,16, 1) = 1   ==      65536 00000000000000001000000000000000
-    vec($_,17, 1) = 1   ==     131072 00000000000000000100000000000000
-    vec($_,18, 1) = 1   ==     262144 00000000000000000010000000000000
-    vec($_,19, 1) = 1   ==     524288 00000000000000000001000000000000
-    vec($_,20, 1) = 1   ==    1048576 00000000000000000000100000000000
-    vec($_,21, 1) = 1   ==    2097152 00000000000000000000010000000000
-    vec($_,22, 1) = 1   ==    4194304 00000000000000000000001000000000
-    vec($_,23, 1) = 1   ==    8388608 00000000000000000000000100000000
-    vec($_,24, 1) = 1   ==   16777216 00000000000000000000000010000000
-    vec($_,25, 1) = 1   ==   33554432 00000000000000000000000001000000
-    vec($_,26, 1) = 1   ==   67108864 00000000000000000000000000100000
-    vec($_,27, 1) = 1   ==  134217728 00000000000000000000000000010000
-    vec($_,28, 1) = 1   ==  268435456 00000000000000000000000000001000
-    vec($_,29, 1) = 1   ==  536870912 00000000000000000000000000000100
-    vec($_,30, 1) = 1   == 1073741824 00000000000000000000000000000010
-    vec($_,31, 1) = 1   == 2147483648 00000000000000000000000000000001
-    vec($_, 0, 2) = 1   ==          1 10000000000000000000000000000000
-    vec($_, 1, 2) = 1   ==          4 00100000000000000000000000000000
-    vec($_, 2, 2) = 1   ==         16 00001000000000000000000000000000
-    vec($_, 3, 2) = 1   ==         64 00000010000000000000000000000000
-    vec($_, 4, 2) = 1   ==        256 00000000100000000000000000000000
-    vec($_, 5, 2) = 1   ==       1024 00000000001000000000000000000000
-    vec($_, 6, 2) = 1   ==       4096 00000000000010000000000000000000
-    vec($_, 7, 2) = 1   ==      16384 00000000000000100000000000000000
-    vec($_, 8, 2) = 1   ==      65536 00000000000000001000000000000000
-    vec($_, 9, 2) = 1   ==     262144 00000000000000000010000000000000
-    vec($_,10, 2) = 1   ==    1048576 00000000000000000000100000000000
-    vec($_,11, 2) = 1   ==    4194304 00000000000000000000001000000000
-    vec($_,12, 2) = 1   ==   16777216 00000000000000000000000010000000
-    vec($_,13, 2) = 1   ==   67108864 00000000000000000000000000100000
-    vec($_,14, 2) = 1   ==  268435456 00000000000000000000000000001000
-    vec($_,15, 2) = 1   == 1073741824 00000000000000000000000000000010
-    vec($_, 0, 2) = 2   ==          2 01000000000000000000000000000000
-    vec($_, 1, 2) = 2   ==          8 00010000000000000000000000000000
-    vec($_, 2, 2) = 2   ==         32 00000100000000000000000000000000
-    vec($_, 3, 2) = 2   ==        128 00000001000000000000000000000000
-    vec($_, 4, 2) = 2   ==        512 00000000010000000000000000000000
-    vec($_, 5, 2) = 2   ==       2048 00000000000100000000000000000000
-    vec($_, 6, 2) = 2   ==       8192 00000000000001000000000000000000
-    vec($_, 7, 2) = 2   ==      32768 00000000000000010000000000000000
-    vec($_, 8, 2) = 2   ==     131072 00000000000000000100000000000000
-    vec($_, 9, 2) = 2   ==     524288 00000000000000000001000000000000
-    vec($_,10, 2) = 2   ==    2097152 00000000000000000000010000000000
-    vec($_,11, 2) = 2   ==    8388608 00000000000000000000000100000000
-    vec($_,12, 2) = 2   ==   33554432 00000000000000000000000001000000
-    vec($_,13, 2) = 2   ==  134217728 00000000000000000000000000010000
-    vec($_,14, 2) = 2   ==  536870912 00000000000000000000000000000100
-    vec($_,15, 2) = 2   == 2147483648 00000000000000000000000000000001
-    vec($_, 0, 4) = 1   ==          1 10000000000000000000000000000000
-    vec($_, 1, 4) = 1   ==         16 00001000000000000000000000000000
-    vec($_, 2, 4) = 1   ==        256 00000000100000000000000000000000
-    vec($_, 3, 4) = 1   ==       4096 00000000000010000000000000000000
-    vec($_, 4, 4) = 1   ==      65536 00000000000000001000000000000000
-    vec($_, 5, 4) = 1   ==    1048576 00000000000000000000100000000000
-    vec($_, 6, 4) = 1   ==   16777216 00000000000000000000000010000000
-    vec($_, 7, 4) = 1   ==  268435456 00000000000000000000000000001000
-    vec($_, 0, 4) = 2   ==          2 01000000000000000000000000000000
-    vec($_, 1, 4) = 2   ==         32 00000100000000000000000000000000
-    vec($_, 2, 4) = 2   ==        512 00000000010000000000000000000000
-    vec($_, 3, 4) = 2   ==       8192 00000000000001000000000000000000
-    vec($_, 4, 4) = 2   ==     131072 00000000000000000100000000000000
-    vec($_, 5, 4) = 2   ==    2097152 00000000000000000000010000000000
-    vec($_, 6, 4) = 2   ==   33554432 00000000000000000000000001000000
-    vec($_, 7, 4) = 2   ==  536870912 00000000000000000000000000000100
-    vec($_, 0, 4) = 4   ==          4 00100000000000000000000000000000
-    vec($_, 1, 4) = 4   ==         64 00000010000000000000000000000000
-    vec($_, 2, 4) = 4   ==       1024 00000000001000000000000000000000
-    vec($_, 3, 4) = 4   ==      16384 00000000000000100000000000000000
-    vec($_, 4, 4) = 4   ==     262144 00000000000000000010000000000000
-    vec($_, 5, 4) = 4   ==    4194304 00000000000000000000001000000000
-    vec($_, 6, 4) = 4   ==   67108864 00000000000000000000000000100000
-    vec($_, 7, 4) = 4   == 1073741824 00000000000000000000000000000010
-    vec($_, 0, 4) = 8   ==          8 00010000000000000000000000000000
-    vec($_, 1, 4) = 8   ==        128 00000001000000000000000000000000
-    vec($_, 2, 4) = 8   ==       2048 00000000000100000000000000000000
-    vec($_, 3, 4) = 8   ==      32768 00000000000000010000000000000000
-    vec($_, 4, 4) = 8   ==     524288 00000000000000000001000000000000
-    vec($_, 5, 4) = 8   ==    8388608 00000000000000000000000100000000
-    vec($_, 6, 4) = 8   ==  134217728 00000000000000000000000000010000
-    vec($_, 7, 4) = 8   == 2147483648 00000000000000000000000000000001
-    vec($_, 0, 8) = 1   ==          1 10000000000000000000000000000000
-    vec($_, 1, 8) = 1   ==        256 00000000100000000000000000000000
-    vec($_, 2, 8) = 1   ==      65536 00000000000000001000000000000000
-    vec($_, 3, 8) = 1   ==   16777216 00000000000000000000000010000000
-    vec($_, 0, 8) = 2   ==          2 01000000000000000000000000000000
-    vec($_, 1, 8) = 2   ==        512 00000000010000000000000000000000
-    vec($_, 2, 8) = 2   ==     131072 00000000000000000100000000000000
-    vec($_, 3, 8) = 2   ==   33554432 00000000000000000000000001000000
-    vec($_, 0, 8) = 4   ==          4 00100000000000000000000000000000
-    vec($_, 1, 8) = 4   ==       1024 00000000001000000000000000000000
-    vec($_, 2, 8) = 4   ==     262144 00000000000000000010000000000000
-    vec($_, 3, 8) = 4   ==   67108864 00000000000000000000000000100000
-    vec($_, 0, 8) = 8   ==          8 00010000000000000000000000000000
-    vec($_, 1, 8) = 8   ==       2048 00000000000100000000000000000000
-    vec($_, 2, 8) = 8   ==     524288 00000000000000000001000000000000
-    vec($_, 3, 8) = 8   ==  134217728 00000000000000000000000000010000
-    vec($_, 0, 8) = 16  ==         16 00001000000000000000000000000000
-    vec($_, 1, 8) = 16  ==       4096 00000000000010000000000000000000
-    vec($_, 2, 8) = 16  ==    1048576 00000000000000000000100000000000
-    vec($_, 3, 8) = 16  ==  268435456 00000000000000000000000000001000
-    vec($_, 0, 8) = 32  ==         32 00000100000000000000000000000000
-    vec($_, 1, 8) = 32  ==       8192 00000000000001000000000000000000
-    vec($_, 2, 8) = 32  ==    2097152 00000000000000000000010000000000
-    vec($_, 3, 8) = 32  ==  536870912 00000000000000000000000000000100
-    vec($_, 0, 8) = 64  ==         64 00000010000000000000000000000000
-    vec($_, 1, 8) = 64  ==      16384 00000000000000100000000000000000
-    vec($_, 2, 8) = 64  ==    4194304 00000000000000000000001000000000
-    vec($_, 3, 8) = 64  == 1073741824 00000000000000000000000000000010
-    vec($_, 0, 8) = 128 ==        128 00000001000000000000000000000000
-    vec($_, 1, 8) = 128 ==      32768 00000000000000010000000000000000
-    vec($_, 2, 8) = 128 ==    8388608 00000000000000000000000100000000
-    vec($_, 3, 8) = 128 == 2147483648 00000000000000000000000000000001
-
-=item wait
-X<wait>
-
-Behaves like wait(2) on your system: it waits for a child
-process to terminate and returns the pid of the deceased process, or
-C<-1> if there are no child processes.  The status is returned in C<$?>
-and C<${^CHILD_ERROR_NATIVE}>.
-Note that a return value of C<-1> could mean that child processes are
-being automatically reaped, as described in L<perlipc>.
-
-If you use wait in your handler for $SIG{CHLD} it may accidentally for the
-child created by qx() or system(). See L<perlipc> for details.
-
-Portability issues: L<perlport/wait>.
-
-=item waitpid PID,FLAGS
-X<waitpid>
-
-Waits for a particular child process to terminate and returns the pid of
-the deceased process, or C<-1> if there is no such child process.  On some
-systems, a value of 0 indicates that there are processes still running.
-The status is returned in C<$?> and C<${^CHILD_ERROR_NATIVE}>.  If you say
-
-    use POSIX ":sys_wait_h";
-    #...
-    do {
-        $kid = waitpid(-1, WNOHANG);
-    } while $kid > 0;
-
-then you can do a non-blocking wait for all pending zombie processes.
-Non-blocking wait is available on machines supporting either the
-waitpid(2) or wait4(2) syscalls.  However, waiting for a particular
-pid with FLAGS of C<0> is implemented everywhere.  (Perl emulates the
-system call by remembering the status values of processes that have
-exited but have not been harvested by the Perl script yet.)
-
-Note that on some systems, a return value of C<-1> could mean that child
-processes are being automatically reaped.  See L<perlipc> for details,
-and for other examples.
-
-Portability issues: L<perlport/waitpid>.
-
-=item wantarray
-X<wantarray> X<context>
-
-Returns true if the context of the currently executing subroutine or
-C<eval> is looking for a list value.  Returns false if the context is
-looking for a scalar.  Returns the undefined value if the context is
-looking for no value (void context).
-
-    return unless defined wantarray; # don't bother doing more
-    my @a = complex_calculation();
-    return wantarray ? @a : "@a";
-
-C<wantarray()>'s result is unspecified in the top level of a file,
-in a C<BEGIN>, C<UNITCHECK>, C<CHECK>, C<INIT> or C<END> block, or
-in a C<DESTROY> method.
-
-This function should have been named wantlist() instead.
-
-=item warn LIST
-X<warn> X<warning> X<STDERR>
-
-Prints the value of LIST to STDERR.  If the last element of LIST does
-not end in a newline, it appends the same file/line number text as C<die>
-does.
-
-If the output is empty and C<$@> already contains a value (typically from a
-previous eval) that value is used after appending C<"\t...caught">
-to C<$@>.  This is useful for staying almost, but not entirely similar to
-C<die>.
-
-If C<$@> is empty then the string C<"Warning: Something's wrong"> is used.
-
-No message is printed if there is a C<$SIG{__WARN__}> handler
-installed.  It is the handler's responsibility to deal with the message
-as it sees fit (like, for instance, converting it into a C<die>).  Most
-handlers must therefore arrange to actually display the
-warnings that they are not prepared to deal with, by calling C<warn>
-again in the handler.  Note that this is quite safe and will not
-produce an endless loop, since C<__WARN__> hooks are not called from
-inside one.
-
-You will find this behavior is slightly different from that of
-C<$SIG{__DIE__}> handlers (which don't suppress the error text, but can
-instead call C<die> again to change it).
-
-Using a C<__WARN__> handler provides a powerful way to silence all
-warnings (even the so-called mandatory ones).  An example:
-
-    # wipe out *all* compile-time warnings
-    BEGIN { $SIG{'__WARN__'} = sub { warn $_[0] if $DOWARN } }
-    my $foo = 10;
-    my $foo = 20;          # no warning about duplicate my $foo,
-                           # but hey, you asked for it!
-    # no compile-time or run-time warnings before here
-    $DOWARN = 1;
-
-    # run-time warnings enabled after here
-    warn "\$foo is alive and $foo!";     # does show up
-
-See L<perlvar> for details on setting C<%SIG> entries and for more
-examples.  See the Carp module for other kinds of warnings using its
-carp() and cluck() functions.
-
-=item when EXPR BLOCK
-X<when>
-
-=item when BLOCK
-
-C<when> is analogous to the C<case> keyword in other languages. Used with a
-C<foreach> loop or the experimental C<given> block, C<when> can be used in
-Perl to implement C<switch>/C<case> like statements.  Available as a
-statement after Perl 5.10 and as a statement modifier after 5.14.  
-Here are three examples:
-
-    use v5.10;
-    foreach (@fruits) {
-        when (/apples?/) {
-            say "I like apples."
-        }
-        when (/oranges?/) {
-            say "I don't like oranges."
-        }
-        default {
-            say "I don't like anything"
-        }
-    }
-
-    # require 5.14 for when as statement modifier
-    use v5.14;
-    foreach (@fruits) {
-	say "I like apples." 	    when /apples?/; 
-	say "I don't like oranges." when /oranges?;
-        default { say "I don't like anything" }
-    }
-
-    use v5.10;
-    given ($fruit) {
-        when (/apples?/) {
-            say "I like apples."
-        }
-        when (/oranges?/) {
-            say "I don't like oranges."
-        }
-        default {
-            say "I don't like anything"
-        }
-    }
-
-See L<perlsyn/"Switch statements"> for detailed information.
-
-=item write FILEHANDLE
-X<write>
-
-=item write EXPR
-
-=item write
-
-Writes a formatted record (possibly multi-line) to the specified FILEHANDLE,
-using the format associated with that file.  By default the format for
-a file is the one having the same name as the filehandle, but the
-format for the current output channel (see the C<select> function) may be set
-explicitly by assigning the name of the format to the C<$~> variable.
-
-Top of form processing is handled automatically:  if there is insufficient
-room on the current page for the formatted record, the page is advanced by
-writing a form feed, a special top-of-page format is used to format the new
-page header before the record is written.  By default, the top-of-page
-format is the name of the filehandle with "_TOP" appended. This would be a
-problem with autovivified filehandles, but it may be dynamically set to the
-format of your choice by assigning the name to the C<$^> variable while
-that filehandle is selected.  The number of lines remaining on the current
-page is in variable C<$->, which can be set to C<0> to force a new page.
-
-If FILEHANDLE is unspecified, output goes to the current default output
-channel, which starts out as STDOUT but may be changed by the
-C<select> operator.  If the FILEHANDLE is an EXPR, then the expression
-is evaluated and the resulting string is used to look up the name of
-the FILEHANDLE at run time.  For more on formats, see L<perlform>.
-
-Note that write is I<not> the opposite of C<read>.  Unfortunately.
-
-=item y///
-
-The transliteration operator.  Same as C<tr///>.  See
-L<perlop/"Quote and Quote-like Operators">.
-
-=back
-
-=cut
diff --git a/cpan/Pod-Perldoc/corpus/utf8.pod b/cpan/Pod-Perldoc/corpus/utf8.pod
deleted file mode 100644
index 0c12b7e2a2f0..000000000000
--- a/cpan/Pod-Perldoc/corpus/utf8.pod
+++ /dev/null
@@ -1,13 +0,0 @@
-=encoding utf8
-
-=head1 NAME
-
-Büster is my cat
-
-=head1 DESCRIPTION
-
-Ingy döt Net is a Perl programmer
-
-The Roman number for 5 is Ⅴ
-
-=cut
diff --git a/t/porting/podcheck.t b/t/porting/podcheck.t
index 1b5cd65402b3..94419e4782b4 100644
--- a/t/porting/podcheck.t
+++ b/t/porting/podcheck.t
@@ -405,9 +405,6 @@ my %excluded_files = (
                         canonicalize("configpm") => 1,
                         canonicalize("miniperl") => 1,
                         canonicalize("perl") => 1,
-                        canonicalize('cpan/Pod-Perldoc/corpus/no-head.pod') => 1,
-                        canonicalize('cpan/Pod-Perldoc/corpus/perlfunc.pod') => 1,
-                        canonicalize('cpan/Pod-Perldoc/corpus/utf8.pod') => 1,
                         canonicalize("lib/unicore/mktables") => 1,
                         canonicalize("dist/devel-ppport/parts/inc/ppphdoc") => 1,
                     );