|AT(1)||General Commands Manual||AT(1)|
queue, examine or delete jobs for later
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:
The options are as follows:
atand 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
atis given a specific queue, only jobs pending in that queue will be shown.
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
teatime (4pm) and
you can have a time-of-day suffixed with
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
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 [
+ count time-units, where the
time-units can be
years (the singular forms are also accepted). You
at to run the job today by suffixing the
today and to run the job tomorrow by
suffixing the time with
next keyword may be used as an alias for
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. To run a job
at midnight in one week's time, you would do
at utility also supports the time
format used by touch(1) (see the
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
_), and the umask are retained
from the time of invocation. An
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. 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
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
An empty /var/cron/at.deny means that every user is allowed to use these commands. This is the default configuration.
at utility exits with one of the
utilities are compliant with the IEEE Std 1003.1-2008
at flags [
batch flags [
as well as the
teatime keyword, are extensions to
IEEE Std 1003.1-2008
(“POSIX.1”) states that
jobs are submitted to the queue “with no time constraints”;
this implementation permits a timespec argument.
The at.allow/deny mechanism is marked by IEEE Std 1003.1-2008 (“POSIX.1”) as being an X/Open System Interfaces option.
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
|March 16, 2018||OpenBSD-current|