NAME

DateTime::Event::Cron - DateTime extension for generating recurrence sets from crontab lines and files.

SYNOPSIS

  use DateTime::Event::Cron;

  # DateTime::Set construction from crontab line
  $crontab = '*/3 15 1-10 3,4,5 */2';
  $set = DateTime::Event::Cron->from_cron($crontab);
  $iter = $set->iterator(after => DateTime->now);
  while (1) {
    my $next = $iter->next;
    my $now  = DateTime->now;
    sleep(($next->subtract_datetime_absolute($now))->seconds);
    # do stuff...
  }

  # List of DateTime::Set objects from crontab file
  @sets = DateTime::Event::Cron->from_crontab(file => '/etc/crontab');
  $now = DateTime->now;
  print "Now: ", $now->datetime, "\n";
  foreach (@sets) {
    my $next = $_->next($now);
    print $next->datetime, "\n";
  }

  # DateTime::Set parameters
  $crontab = '* * * * *';

  $now = DateTime->now;
  %set_parms = ( after => $now );
  $set = DateTime::Event::Cron->from_cron(cron => $crontab, %set_parms);
  $dt = $set->next;
  print "Now: ", $now->datetime, " and next: ", $dt->datetime, "\n";

  # Spans for DateTime::Set
  $crontab = '* * * * *';
  $now = DateTime->now;
  $now2 = $now->clone;
  $span = DateTime::Span->from_datetimes(
            start => $now->add(minutes => 1),
	    end   => $now2->add(hours => 1),
	  );
  %parms = (cron => $crontab, span => $span);
  $set = DateTime::Event::Cron->from_cron(%parms);
  # ...do things with the DateTime::Set

  # Every RTFCT relative to 12am Jan 1st this year
  $crontab = '7-10 6,12-15 10-28/2 */3 3,4,5';
  $date = DateTime->now->truncate(to => 'year');
  $set = DateTime::Event::Cron->from_cron(cron => $crontab, after => $date);

  # Rather than generating DateTime::Set objects, next/prev
  # calculations can be made directly:

  # Every day at 10am, 2pm, and 6pm. Reference date
  # defaults to DateTime->now.
  $crontab = '10,14,18 * * * *';
  $dtc = DateTime::Event::Cron->new_from_cron(cron => $crontab);
  $next_datetime = $dtc->next;
  $last_datetime = $dtc->previous;
  ...

  # List of DateTime::Event::Cron objects from
  # crontab file
  @dtc = DateTime::Event::Cron->new_from_crontab(file => '/etc/crontab');

  # Full cron lines with user, such as from /etc/crontab
  # or files in /etc/cron.d, are supported and auto-detected:
  $crontab = '* * * * * gump /bin/date';
  $dtc = DateTime::Event::Cron->new(cron => $crontab);

  # Auto-detection of users is disabled if you explicitly
  # enable/disable via the user_mode parameter:
  $dtc = DateTime::Event::Cron->new(cron => $crontab, user_mode => 1);
  my $user = $dtc->user;
  my $command = $dtc->command;

  # Unparsed original cron entry
  my $original = $dtc->original;

DESCRIPTION

DateTime::Event::Cron generated DateTime events or DateTime::Set objects based on crontab-style entries.

METHODS

The cron fields are typical crontab-style entries. For more information, see crontab(5) and extensions described in Set::Crontab. The fields can be passed as a single string or as a reference to an array containing each field. Only the first five fields are retained.

DateTime::Set Factories

See DateTime::Set for methods provided by Set objects, such as next() and previous().

from_cron($cronline)
from_cron(cron => $cronline, %parms, %set_parms): Generates a DateTime::Set recurrence for the cron line provided. See new() for details on %parms. Optionally takes parameters for DateTime::Set.
from_crontab(file => $crontab_fh, %parms, %set_parms): Returns a list of DateTime::Set recurrences based on lines from a crontab file. $crontab_fh can be either a filename or filehandle reference. See new() for details on %parm. Optionally takes parameters for DateTime::Set which will be passed along to each set for each line.
as_set(%set_parms): Generates a DateTime::Set recurrence from an existing DateTime::Event::Cron object.

Constructors

new_from_cron(cron => $cronstring, %parms): Returns a DateTime::Event::Cron object based on the cron specification. Optional parameters include the boolean 'user_mode' which indicates that the crontab entry includes a username column before the command.
new_from_crontab(file => $fh, %parms): Returns a list of DateTime::Event::Cron objects based on the lines of a crontab file. $fh can be either a filename or a filehandle reference. Optional parameters include the boolean 'user_mode' as mentioned above.

Other methods

next()
next($date): Returns the next valid datetime according to the cron specification. $date defaults to DateTime->now unless provided.
previous()
previous($date): Returns the previous valid datetime according to the cron specification. $date defaults to DateTime->now unless provided.
increment($date)
decrement($date): Same as next() and previous() except that the provided datetime is modified to the new datetime.
valid($date): Returns whether the given datetime is valid under the current cron specification. Cron dates are only accurate to the minute -- datetimes with seconds greater than 0 are invalid by default. (note: never fear, all methods accepting dates will accept invalid dates -- they will simply be rounded to the next nearest valid date in all cases except this particular method)
command(): Returns the command string, if any, from the original crontab entry. Currently no expansion is performed such as resolving environment variables, etc.
user(): Returns the username under which this cron command was to be executed, assuming such a field was present in the original cron entry.
original(): Returns the original, unparsed cron string including any user or command fields.

AUTHOR

Matthew P. Sisk <sisk@mojotoad.com>