Schedule::At(3) OS independent interface to the Unix 'at' command


require Schedule::At;
Schedule::At::add(TIME => $string, COMMAND => $string [, TAG =>$string]);
Schedule::At::add(TIME => $string, COMMAND => \@array [, TAG =>$string]);
Schedule::At::add(TIME => $string, FILE => $string)
%jobs = Schedule::At::getJobs();
%jobs = Schedule::At::getJobs(JOBID => $string);
%jobs = Schedule::At::getJobs(TAG => $string);
Schedule::At::readJobs(JOBID => $string);
Schedule::At::readJobs(TAG => $string);
Schedule::At::remove(JOBID => $string);
Schedule::At::remove(TAG => $string);


This modules provides an OS independent interface to 'at', the Unix command that allows you to execute commands at a specified time.
Adds a new job to the at queue.

You have to specify a TIME and a command to execute. The TIME has a common format: YYYYMMDDHHmm where YYYY is the year (4 digits), MM the month (01-12), DD is the day (01-31), HH the hour (00-23) and mm the minutes.

The command is passed with the COMMAND or the FILE parameter. COMMAND can be used to pass the command as an string, or an array of commands, and FILE to read the commands from a file.

The optional parameter TAG serves as an application specific way to identify a job or a set of jobs.

Returns 0 on success or a value != 0 if an error occurred.

Read the job content identified by the JOBID or TAG parameters.

Returns a hash of JOBID => $string where $string is the the job content. As the operating systems usually add a few environment settings, the content is longer than the command provided when adding the job.

Remove an at job.

You identify the job to be deleted using the JOBID parameter (an opaque string returned by the getJobs subroutine). You can also specify a job or a set of jobs to delete with the TAG parameter, removing all the jobs that have the same tag (as specified with the add subroutine).

Used with JOBID, returns 0 on success or a value != 0 if an error occurred. Used with TAG, returns a hash reference where the keys are the JOBID of the jobs found and the values indicate the success of the remove operation.

Called with no params returns a hash with all the current jobs or dies if an error has occurred. It's possible to specify the TAG or JOBID parameters so only matching jobs are returned. For each job the key is a JOBID (an OS dependent string that shouldn't be interpreted), and the value is a hash reference.

This hash reference points to a hash with the keys:

An OS dependent string specifying the time to execute the command
The tag specified in the Schedule::At::add subroutine

Configuration Variables

  • $Schedule::At::SHELL

    This variable can be used to specify shell for execution of the scheduled command. Can be useful for example when scheduling from CGI script and the account of the user under which httpd runs is locked by using '/bin/false' or similar as a shell.


 use Schedule::At;
 # 1
 Schedule::At::add (TIME => '199801181530', COMMAND => 'ls', 
        TAG => 'ScheduleAt');
 # 2
 @cmdlist = ("ls", "echo hello world");
 Schedule::At::add (TIME => '199801181630', COMMAND => \@cmdlist, 
        TAG => 'ScheduleAt');
 # 3
 Schedule::At::add (TIME => '199801181730', COMMAND => 'df');
 # This will remove #1 and #2 but no #3
 Schedule::At::remove (TAG => 'ScheduleAt');
 my %atJobs = Schedule::At::getJobs();
 foreach my $job (values %atJobs) {
        print "\t", $job->{JOBID}, "\t", $job->{TIME}, ' ', 
                ($job->{TAG} || ''), "\n";


Jose A. Rodriguez (jose AT