at, batch - queue, examine or delete jobs for later execution
at [-blmr] [-f file] [-q queue] -t time_arg
at [-blmr] [-f file] [-q queue] timespec
at -c job [job ...]
batch [-m] [-f file] [-q queue] [timespec]
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
the SHELL environment variable. If SHELL is not set, the
shell in the
user's password database entry is used instead. If all else
will be used.
The related programs are as follows:
at Executes commands at a specified time.
batch Executes commands when system load levels permit.
words, when the load average drops below 1.5, or the
in the invocation of cron(8).
The options are as follows:
-b An alias for batch.
-c Prints the jobs listed on the command line to standard output.
Reads the job from file rather than standard input.
-l Lists the user's pending jobs, unless the user is
In that case, all users' jobs are listed.
-m Send mail to the user when the job has completed,
even if there
was no output.
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
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
queue, only jobs pending in that queue will be
-r Remove the specified job(s) from the at queue.
Specify the job time using the format specified by
argument should be in the form [[CC]YY]MMDDhhmm[.SS]
pair of letters represents the following:
CC The first two digits of the year (the
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
If the CC and YY letter pairs are not specified, the
to the current year. If the SS letter pair is
the value defaults to 0.
-v When used in conjunction with the -l option, shows
not yet deleted jobs in the queue.
at allows some moderately complex timespec specifications.
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
suffixed with ``AM'' or ``PM'' for running in the morning or
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
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 considered
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 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. To run a job at 1am tomorrow, you would do at 1am
The at utility also supports the time format used by
touch(1) (see 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 user
ID. The user
will be mailed standard error and standard output from
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
For non-root users, permission to run at is determined by
/var/cron/at.allow and /var/cron/at.deny. Note: these files
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
An empty /var/cron/at.deny means that every user is allowed
commands. This is the default configuration.
/var/cron/atjobs directory containing job files
/var/cron/at.allow allow permission control
/var/cron/at.deny deny permission control
nice(1), sh(1), touch(1), umask(2), cron(8), sendmail(8)
at was mostly written by Thomas Koenig <email@example.com>. The
time parsing routines are by
David Parsons <firstname.lastname@example.org>.
at and batch as presently implemented are not suitable when
competing for resources. If this is the case for your site,
want to consider another batch system, such as nqs.
OpenBSD 3.6 May 13, 2002
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