AT(1) BSD General Commands Manual AT(1)
at, batch, atq, atrm -- queue, examine or delete jobs for later execution
at [-bdlmrVv] [-f file] [-q queue] -t [[CC]YY]MMDDhhmm[.SS]
at [-bdlmrVv] [-f file] [-q queue] time
at [-V] -c job [job ...]
atq [-Vv] [-q queue]
atrm [-V] job [job ...]
batch [-mVv] [-f file] [-q queue] [-t [[CC]YY]MMDDhhmm[.SS]]
batch [-mVv] [-f file] [-q queue] [time]
at and batch read commands from standard input or a specified file which are to be 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 1.5, or the value specified in
the invocation of atrun(8).
at 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.) 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 MMDDYY or MM/DD/YY or DD.MM.YY. The specification of a
date must follow the specification of the time of day. You can also give times like [now] or [now] '+ count %time-units', where the time-
units can be 'minutes', 'hours', 'days', 'weeks', 'months', or 'years' and you can tell at to run the job today by suffixing the time with
'today' and to run the job tomorrow 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
and to run a job at 1am tomorrow, you would do
at 1am tomorrow.
Alternatively the time may be specified in a language-neutral fashion by using the -t options.
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 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(1). 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, permission to use at is determined by the files /var/at/at.allow and
If the file /var/at/at.allow exists, only usernames mentioned in it are allowed to use at.
If /var/at/at.allow does not exist, /var/at/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.
An empty /var/at/at.deny means that every user is allowed use these commands. This is the default configuration.
-b Is an alias for batch.
-c Cats the jobs listed on the command line to standard output.
-d Is an alias for atrm.
-f file Reads the job from file rather than standard input.
-l Is an alias for atq.
-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 single 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 atq is given a specific queue, it will only show jobs pending in that queue.
-r Is an alias for atrm.
-t For both at and batch, the time may be specified in a language-neutral format consisting of:
CC The first two digits of the year (the century).
YY The second two digits of the year. If YY is specified, but CC is not, a value for YY between 69 and 99
results in a CC value of 19. Otherwise, a CC value of 20 is used.
MM The month of the year, from 01 to 12.
DD The day of the month, from 01 to 31.
hh The hour of the day, from 00 to 23.
mm The minute of the hour, from 00 to 59.
SS The second of the minute, from 00 to 61.
-V Prints the version number to standard error.
-v For atq, shows completed but not yet deleted jobs in the queue. Otherwise shows the time the job will be executed.
/var/at/jobs Directory containing job files
/var/at/spool Directory containing output spool files
/var/run/utmp Login records
/var/at/at.allow Allow permission control
/var/at/at.deny Deny permission control
/var/at/.lockfile Job-creation lock file.
nice(1), sendmail(1), sh(1), umask(2), atrun(8), cron(8)
The at and batch utilities conform to IEEE Std 1003.2-1992 (``POSIX.2'').
At was mostly written by Thomas Koenig <email@example.com>. The time parsing routines are by David Parsons <firstname.lastname@example.org>.
If the file /var/run/utmp 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.
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.
March 10, 2008 BSD