AT(1)                      OpenBSD Reference Manual                      AT(1)

NAME
     at, batch - queue, examine or delete jobs for later execution

SYNOPSIS
     at [-bm] [-f file] [-l [user ...]] [-q queue] -t time_arg | timespec
     at -c | -r job ...
     batch [-m] [-f file] [-q queue] [timespec]

DESCRIPTION
     at and batch read commands from standard input or a specified file which
     are to be executed at a later time, via the user's shell as specified by
     the SHELL environment variable.  If SHELL is not set, the shell in the
     user's password database entry is used instead.  If all else fails, sh(1)
     will be used.

     The related programs are as follows:

     at      Executes commands at a specified time.

     batch   Executes commands when system load levels permit.  In other
             words, when the load average drops below 1.5, or the value speci-
             fied in the invocation of cron(8).

     The options are as follows:

     -b      An alias for batch.

     -c job ...
             Prints the jobs listed on the command line to standard output.

     -f file
             Reads the job from file rather than standard input.

     -l [user ...]
             Displays the queue of jobs which are currently awaiting execu-
             tion.  If a user argument is specified, only jobs belonging to
             that user will be displayed.  Unless the user is the superuser,
             only the user's own jobs will be displayed.

     -m      Send mail to the user when the job has completed, even if there
             was no output.

     -q queue
             Uses the specified queue.  A queue designation consists of a sin-
             gle letter.  Valid queue designations range from a to z and A to
             Z.  The c queue is the default for at and the E queue for batch.
             Queues with higher letters run with increased niceness.  If a job
             is submitted to a queue designated with an uppercase letter, it
             is treated as if it had been submitted to batch at that time.  If
             the user specified the -l option and at is given a specific
             queue, only jobs pending in that queue will be shown.

     -r job ...
             Remove the specified job(s) from the at queue.

     -t time_arg
             Specify the job time using the format specified by touch(1).  The
             argument should be in the form [[CC]YY]MMDDhhmm[.SS] where each
             pair of letters represents the following:

                   CC      The first two digits of the year (the century).
                   YY      The second two digits of the year.
                   MM      The month of the year, from 1 to 12.
                   DD      the day of the month, from 1 to 31.
                   hh      The hour of the day, from 0 to 23.
                   mm      The minute of the hour, from 0 to 59.
                   SS      The second of the minute, from 0 to 61.

             If the CC and YY letter pairs are not specified, the values de-
             fault to the current year.  If the SS letter pair is not speci-
             fied, the value defaults to 0.

     at allows some moderately complex timespec specifications.  It accepts
     times of the form HHMM or HH:MM to run a job at a specific time of day.
     (If that time is already past, the next day is assumed.)  You may also
     specify midnight, noon, or teatime (4pm) and you can have a time-of-day
     suffixed with ``AM'' or ``PM'' for running in the morning or the evening.
     You can also say what day the job will be run, by giving a date in the
     form month-name day with an optional year, or giving a date of the form
     DD.MM.CCYY, DD.MM.YY, MM/DD/CCYY, MM/DD/YY, MMDDCCYY, or MMDDYY.

     The year may be given as two or four digits.  If the year is given as two
     digits, it is taken to occur as soon as possible in the future, which may
     be in the next century -- unless it's last year, in which case it's con-
     sidered to be a typo.

     The specification of a date must follow the specification of the time of
     day.  You can also give times like [`now'] + count time-units, where the
     time-units can be minutes, hours, days, or weeks and you can tell at to
     run the job today by suffixing the time with today and to run the job to-
     morrow by suffixing the time with tomorrow.

     For example, to run a job at 4pm three days from now, you would do at 4pm
     + 3 days.  To run a job at 10:00am on July 31, you would do at 10am Jul
     31.  To run a job at 1am tomorrow, you would do at 1am tomorrow.

     The at utility also supports the time format used by touch(1) (see the -t
     option).

     For both at and batch, commands are read from standard input (or the file
     specified with the -f option) and executed.  The working directory, the
     environment (except for the variables TERM, TERMCAP, DISPLAY, and _), and
     the umask are retained from the time of invocation.  An at or batch com-
     mand invoked from a su(1) shell will retain the current user ID.  The us-
     er will be mailed standard error and standard output from his commands,
     if any.  Mail will be sent using sendmail(8).  If at is executed from a
     su(1) shell, the owner of the login shell will receive the mail.

     For non-root users, permission to run at is determined by the files
     /var/cron/at.allow and /var/cron/at.deny.  Note: these files must be
     readable by group crontab (if they exist).

     If the file /var/cron/at.allow exists, only usernames mentioned in it are
     allowed to use at.  If /var/cron/at.allow does not exist,
     /var/cron/at.deny is checked.  Every username not mentioned in it is then
     allowed to use at.  If neither exists, only the superuser is allowed to
     run at.

     An empty /var/cron/at.deny means that every user is allowed to use these
     commands.  This is the default configuration.

FILES
     /var/cron/atjobs    directory containing job files
     /var/cron/at.allow  allow permission control
     /var/cron/at.deny   deny permission control

SEE ALSO
     atq(1), atrm(1), nice(1), sh(1), touch(1), umask(2), cron(8), sendmail(8)

STANDARDS
     The at and batch utilities are compliant with the IEEE Std 1003.1-2008
     (``POSIX'') specification.

     The at flags [-bc] and the batch flags [-fmq] are extensions to that
     specification.

     Behaviour for the -l flag differs between this implementation and IEEE
     Std 1003.1-2008 (``POSIX'').

AUTHORS
     at was mostly written by Thomas Koenig <ig25@rz.uni-karlsruhe.de>.  The
     time parsing routines are by David Parsons <orc@pell.chi.il.us>.

BUGS
     at and batch as presently implemented are not suitable when users are
     competing for resources.  If this is the case for your site, you might
     want to consider another batch system, such as nqs.

OpenBSD 4.7                    December 7, 2009                              3
