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Getopt::Std - Process single-character options with option clustering


    use Getopt::Std;

    # Classical usage, slightly extended:
    # - for options that take an argument, return only the last one
    # - for options that don't, return a string containing the option
    #   name as many times as the option was specified

    my Str:D %opts = getopts('ho:V', @*ARGS);
    CATCH { when X::Getopt::Std { .message.note; usage } };

    version() if %opts<V>;
    usage(True) if %opts<h>;
    exit(0) if %opts{<V h>}:k;

    my $outfile = %opts<o> // 'a.out';

    # "All options" usage:
    # - for options that take an argument, return an array of all
    #   the arguments supplied if specified more than once
    # - for options that don't, return the option name as many times
    #   as it was specified

    my %opts = getopts-all('o:v', @*ARGS);

    $verbose_level = %opts<v>.elems;

    for %opts<o> -> $fname {
        process_outfile $fname;

    # Permute usage (with both getopts() and getopts-all()):
    # - don't stop at the first non-option argument, look for more
    #   arguments starting with a dash
    # - stop at an -- argument

    my Str:D %opts;
    %opts = getopts('ho:V', @*ARGS, :permute);


This module exports the getopts() and getopts-all()> functions for parsing command-line arguments similarly to the POSIX getopt(3) standard C library routine.

The options are single letters (no long options) preceded by a single dash character. Options that do not accept arguments may be clustered (e.g. -hV for -h and -V); the last one may be an option that accepts an argument (e.g. -vo outfile.txt). Options that accept arguments may have their argument "glued" to the option or in the next element of the arguments array, i.e. -ooutfile is equivalent to -o outfile. There is no equals character between an option and its argument; if one is supplied, it will be considered the first character of the argument.

If an unrecognized option character is supplied in the arguments array, getopts() will throw an exception. Otherwise it will return a hash with the options found in the arguments array. The key in the returned hash is the option name (e.g. h or o); the value is the option argument for options that accept one or the option name (as many times as it has been specified) for options that do not.


  • sub getopts

    sub getopts(Str:D $optstr, @args, Bool :$nonopts,
        Bool :$permute, Bool :$unknown) returns Hash[Str:D]

    Look for the command-line options specified in $optstr in the @args array. Return the options found in a hash, leave only the non-option arguments in the @args array.

    Note that if an option is specified more than once on the command line, getopts() will only record the last argument in the returned hash; see also the getopts-all() function below.

    The :permute flag specifies whether option parsing should stop at the first non-option argument, or go on and process any other arguments starting with a dash. A double dash (--) stops the processing in this case, too.

    The :unknown flag controls the handling of unknown options - ones not specified in the $optstr, but present in the @args. If it is false (the default), getopts() will throw an exception; otherwise, the unknown option character will be present in the returned hash as an argument to a : option and getopts() will still succeed. This is similar to the behavior of some getopt(3) implementations if $optstr starts with a : character.

    The :nonopts flag makes getopts() treat each non-option argument as an argument to an option with a character code 1. This is similar to the behavior of some getopt(3) implementations if $optstr starts with a - character. The :permute flag is redundant if :nonopts is specified since the processing will not stop until the arguments array has been exhausted.

    Throws an X::Getopt::Std exception if an invalid option string has been specified or an unknown option has been found in the arguments array.

    Current API available since version 1.0.0.

  • sub getopts-all

    sub getopts-all(Str:D $optstr, @args, Bool :$nonopts,
        Bool :$permute, Bool :$unknown) returns Hash[Array[Str:D]]

    Same as the getopts() function, but all the returned values are arrays containing all the specified arguments if any options have been specified more than once.

    For example, the command line -vI foo -I bar -v, matched against an option string of I:v, would produce { :I<bar> :v<vv> } with getopts() and { :I(['foo', 'bar']) :v(['v', 'v']) } with getopts-all().

    Current API available since version 1.0.0.


Peter Pentchev <>


Copyright (C) 2016, 2017, 2020 Peter Pentchev


The Getopt::Std module is distributed under the terms of the Artistic License 2.0. For more details, see the full text of the license in the file LICENSE in the source distribution.


A Perl 6 module for parsing command-line options




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