at, batch - execute commands at a later time
Syntaxat time [day] [file]
The and commands use a copy of the named file (standard input default)
as input to the or commands at a later time. When the job is run, a
command to the current directory is inserted at the beginning, followed
by assignments to all environment variables. Also, when the job is
run, it uses the user and group ID of the creator of the named file.
The command allows the user to specify when to execute the commands;
jobs queued with the command execute the commands when the load level
of the system permits.
The environment variables, current directory, and are retained when the
commands are executed. However, open files, traps, and priority are
Users are permitted to use the and commands if their name appears in
the file. If that file does not exist, the file is checked to deter‐
mine if the user should be denied access to and If neither file exists,
only the superuser is allowed to submit a job. If only the file exists
and is empty, global usage is permitted. The files consist of one user
name per line.
The time argument is 1 to 4 digits. It can, but does not have to be,
followed by A, P, N or M which stand for AM, PM, noon, or midnight,
respectively. The A, P, N, and M suffixes are not case-sensitive. One
and two digit numbers are interpreted as hours, three and four digits
as hours and minutes. If three digits are specified, the first digit is
interpreted as an hour in the range 0-9, and the second and third dig‐
its as minutes. If no letters follow the digits, a 24 hour clock time
In addition to 1-4 digits, and suffixes A, P, M, N, you can also spec‐
The optional day argument is either a month name followed by a day num‐
ber or by a day of the week. If the word week follows the day number,
the or command is invoked seven days after the day number. Both com‐
mands also recognize standard abbreviations for the days of the week
and months of the year. The following are examples of legitimate com‐
at 8am jan 24
at 1530 fr week
The programs are executed by periodic execution of the command from The
granularity of depends upon how often is executed. The command exam‐
ines the file every minute. The file determines when is executed. The
default is every 15 minutes on the 1/4 hour. You can edit the file to
make the command run more or less frequently.
Standard output or error output is lost unless it is redirected.
The and commands write the job number to standard error.
Options-r Removes jobs previously scheduled by or The job
number is the number reported at invocation by or
Only the superuser is allowed to remove another
-l Lists all job numbers for all jobs submitted by the
user issuing the command. Even if the user is
root, only numbers for jobs submitted by root are
displayed. To see the numbers of all jobs submit‐
ted, enter the following command:
% ls -l /usr/spool/at
Due to the granularity of the execution of the command, there may be
bugs in scheduling jobs to run almost exactly 24 hours into the future.
The command starts jobs only at midnight. Use the command whenever
Error messages about various syntax errors and times that are out of
range are reported.
/usr/lib/atrun executor run by cron(8)
yy.ddd.hhhh.* activity for year yy, day dd, hour hhhh.
lasttimedone last hhhh
past activities in progress
/usr/spool/at/at.allowlist of allowed users
/usr/spool/at/at.denylist of denied users
/usr/spool/at spool directory
/usr/lib/cron XOPEN compatibility
See Alsocrontab(5), cron(8)at(1)