AT(1) General Commands Manual AT(1)
NAME
at, batch, atq, atrm – queue, examine, or delete jobs for later execution
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 specified
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 specified 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,
permission 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 comments.
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
information 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 single
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 specified, 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)
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⟩.
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.
macOS 12.1 January 13, 2002 macOS 12.1