Time::Crontab for perl6
Perl6
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README.md

NAME

Time::Crontab for perl6

SYNOPSIS

use Time::Crontab;
my $crontab = "* * * * *";
my $tc = Time::Crontab.new(:$crontab);
if $tc.match(DateTime.now, :truncate(True)) { ..... }

METHODS

  • new(Str :$crontab!, Int :$timezone = 0) returns DateTime:D

  • match(DateTime $datetime, Bool :$truncate = False) returns Bool:D

Matches the $datetime against the crontab specification. Since the crontab's smallest granulation is minute wise there is a option to $truncate the $datetime to minutes when it comes to consideration if the $datetime matches the $crontab.

  • next-datetime(DateTime $datetie) returns DateTime:D

Calculates the next execution right after $datetime.

SYNTAX OF THE CRONTAB

Field name   Allowed values  Allowed special characters
Minutes      0-59            * / , - !
Hours        0-23            * / , - !
Day of month 1-31            * / , - !
Month        1-12 or JAN-DEC * / , - !
Day of week  0-6 or SUN-SAT  * / , - !
  • * means anything. The actual values depends on the field.
  • / is a stepping. This special character must be followed bit a number, which decribes the step size.
  • , can be used to list different values, or ranges.
  • - indicates a range.
  • ! excludes a value.

The names of the month or day of the week are the first 3 characters of their english names. They are case insensetive.

DAY OF MONTH VS DAY OF WEEK

The Handling of the Day of Week and Day of Month is quite delicate. In the case that the Day of Week field is set to any (*) you basically dont care for it.

This is borrowd from the crontab 5 manpage

 Note: The day of a command's execution can be specified by two fields — day of month, and day of week.  If both fields are restricted (i.e., aren't *), the command  will  be
 run when either field matches the current time.  For example,
 ``30  4  1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th of each month, plus every Friday. One can, however, achieve the desired result by adding a
 test to the command (see the last example in EXAMPLE CRON FILE below).

 # run five minutes after midnight, every day
 5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
 # run at 2:15pm on the first of every month -- output mailed to paul
 15 14 1 * *     $HOME/bin/monthly
 # run at 10 pm on weekdays, annoy Joe
 0 22 * * 1-5    mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
 23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
 5 4 * * sun     echo "run at 5 after 4 every sunday"
 # Run on every second Saturday of the month
 0 4 8-14 * *    test $(date +\%u) -eq 6 && echo "2nd Saturday"