Programmatically add a cronjob

add_cronjob.pl

sub add_cronjob {
   my ($spec) = @_;

   local *getCmd = sub {
      my @chunks = split(/\s+/, $_[0], 6);
      return $chunks[5];
   };

   my $crontext_old = `crontab -l`;
   my $existing = grep { getCmd($spec) eq getCmd($_) } split(/\n/, $crontext_old);
   return if $existing;

   open(CRONTAB, "| crontab -");
   print CRONTAB $crontext_old;
   print CRONTAB "$spec\n";
   close(CRONTAB);
}