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 specifica-
tion 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
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 /var/at/at.deny.
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
-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 out-
-q queue Uses the specified queue. A queue designation consists of a single let-
ter. 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 <firstname.lastname@example.org>. The time parsing rou-
tines are by David Parsons <email@example.com>.
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 sys-
tem, such as nqs.
BSD March 10, 2008 BSD