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
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 specified
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.
-f file
Reads the job from file rather than standard input.
-l Lists the user's pending jobs, unless the user is
the superuser.
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.
-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
the user specified the -l option and at is given a
specific
queue, only jobs pending in that queue will be
shown.
-r 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 default
to the current year. If the SS letter pair is
not specified,
the value defaults to 0.
-v When used in conjunction with the -l option, shows
completed but
not yet deleted jobs in the queue.
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 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
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 command
invoked from a su(1) shell will retain the current user
ID. The user
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
use these
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 protected]-karlsruhe.de>. The
time parsing routines are by
David Parsons <[email protected]>.
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 3.6 May 13, 2002
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