AT(1)                     BSD General Commands Manual                    AT(1)

NAME
     at, batch, atq, atrm -- queue, examine, or delete jobs for later execu-
     tion

SYNOPSIS
     at [-q queue] [-f file] [-mldbv] time
     at [-q queue] [-f file] [-mldbv] -t [[CC]YY]MMDDhhmm[.SS]
     at -c job [job ...]
     at -l [job ...]
     at -l -q queue
     at -r job [job ...]

     atq [-q queue] [-v]

     atrm job [job ...]

     batch [-q queue] [-f file] [-mv] [time]

DESCRIPTION
     The at and batch utilities read commands from standard input or a speci-
     fied file.  The commands are executed at a later time, using sh(1).

     at      executes commands at a specified time;

     atq     lists the user's pending jobs, unless the user is the superuser;
             in that case, everybody's jobs are listed;

     atrm    deletes jobs;

     batch   executes commands when system load levels permit; in other words,
             when the load average drops below _LOADAVG_MX (1.5), or the value
             specified in the invocation of atrun.

     The at utility allows some moderately complex time 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.)  As an
     alternative, the following keywords may be specified: midnight, noon, or
     teatime (4pm) and time-of-day may be suffixed with AM or PM for running
     in the morning or the evening.  The day on which the job is to be run may
     also be specified by giving a date in the form month-name day with an
     optional year, or giving a date of the forms DD.MM.YYYY, DD.MM.YY,
     MM/DD/YYYY, MM/DD/YY, MMDDYYYY, or MMDDYY.  The specification of a date
     must follow the specification of the time of day.  Time can also be spec-
     ified as: [now] + count time-units, where the time-units can be minutes,
     hours, days, weeks, months or years and at may be told to run the job
     today by suffixing the time with today and to run the job tomorrow by
     suffixing the time with tomorrow.  The shortcut next can be used instead
     of + 1.

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

     The at utility also supports the POSIX time format (see -t option).

     For both at and batch, commands are read from standard input or the file
     specified with the -f option.  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 command invoked
     from a su(1) shell will retain the current userid.  The user will be
     mailed standard error and standard output from his commands, if any.
     Mail will be sent using the command sendmail(8).  If at is executed from
     a su(1) shell, the owner of the login shell will receive the mail.

     The superuser may use these commands in any case.  For other users, per-
     mission to use at is determined by the files _PERM_PATH/at.allow and
     _PERM_PATH/at.deny.

     If the file _PERM_PATH/at.allow exists, only usernames mentioned in it
     are allowed to use at.  In these two files, a user is considered to be
     listed only if the user name has no blank or other characters before it
     on its line and a newline character immediately after the name, even at
     the end of the file.  Other lines are ignored and may be used for com-
     ments.

     If _PERM_PATH/at.allow does not exist, _PERM_PATH/at.deny is checked,
     every username not mentioned in it is then allowed to use at.

     If neither exists, only the superuser is allowed use of at.

IMPLEMENTATION NOTES
     Note that at is implemented through the launchd(8) daemon periodically
     invoking atrun(8), which is disabled by default.  See atrun(8) for infor-
     mation about enabling atrun.

OPTIONS
     -b      Is an alias for batch.

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

     -d      Is an alias for atrm (this option is deprecated; use -r instead).

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

     -l      With no arguments, list all jobs for the invoking user.  If one
             or more job numbers are given, list only those jobs.

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

     -q queue
             Use 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 _DEFAULT_AT_QUEUE queue (a) is the default for at and the
             _DEFAULT_BATCH_QUEUE queue (b) is the default 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
             atq is given a specific queue, it will only show jobs pending in
             that queue.

     -r      Remove the specified jobs.

     -t      Specify the job time using the POSIX time format.  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
             default to the current year.  If the SS letter pair is not speci-
             fied, the value defaults to 0.

     -v      For atq, shows completed but not yet deleted jobs in the queue;
             otherwise shows the time the job will be executed.

FILES
     _ATJOB_DIR            directory containing job files
                           (/usr/lib/cron/jobs/)
     _ATJOB_DIR/_LOCKFILE  job-creation lock file (/usr/lib/cron/jobs/...)
     _ATSPOOL_DIR          directory containing output spool files
                           (/usr/lib/cron/spool/)
     _PERM_PATH/at.allow   allow permission control (/usr/lib/cron/at.allow)
     _PERM_PATH/at.deny    deny permission control (/usr/lib/cron/at.deny)
     /var/run/utmpx        login records

SEE ALSO
     nice(1), sh(1), umask(2), compat(5), atrun(8), cron(8), sendmail(8)

BUGS
     If the file /var/run/utmpx is not available or corrupted, or if the user
     is not logged on at the time at is invoked, the mail is sent to the
     userid found in the environment variable LOGNAME.  If that is undefined
     or empty, the current userid is assumed.

     The at and batch utilities as presently implemented are not suitable when
     users are competing for resources.  If this is the case, another batch
     system such as nqs may be more suitable.

     Specifying a date past 2038 may not work on some systems.

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>, with minor enhancements by
     Joe Halpin <joe.halpin@attbi.com>.

BSD                            January 13, 2002                            BSD