--- name: "at" section: "1" platform: "macos" package: "system_cmds" version: "1042.120.1" release: "macOS 26.5" platforms: ["linux", "freebsd", "openbsd", "macos"] url: "https://new.carta.tech/at" --- # at(1) queue, examine or delete jobs for later execution ## 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*\] *MM**DD**hh**mm*\[.*SS*\] **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 which are to be executed at a later time, using [sh(1)](/sh/1.md). - **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 1.5 times number of active CPUs, 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*, *PM*, or *UTC* for running in the morning, the evening, or in UTC time. 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 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)](/su/1.md) 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)](/sendmail/8.md). If **at** is executed from a [su(1)](/su/1.md) 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 */usr/lib/cron/at.allow* and */usr/lib/cron/at.deny*. If the file */usr/lib/cron/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 */usr/lib/cron/at.allow* does not exist, */usr/lib/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 use of **at**. This is the default configuration. ## IMPLEMENTATION NOTES Note that **at** is implemented through the launchd(8) daemon periodically invoking [atrun(8)](/atrun/8.md), which is disabled by default. See [atrun(8)](/atrun/8.md) for information about enabling **atrun**. ## OPTIONS - **-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 *a* queue is the default for **at** and the *b* 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 **atq** is given a specific queue, it will only show jobs pending in that queue. - **-m** Send mail to the user when the job has completed even if there was no output. - **-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. - **-d** Is an alias for **atrm** (this option is deprecated; use **-r** instead). - **-b** Is an alias for **batch**. - **-v** For **atq**, shows completed but not yet deleted jobs in the queue; otherwise shows the time the job will be executed. - **-c** Cat the jobs listed on the command line to standard output. - **-r** Remove the specified jobs. - **-t** Specify the job time using the time format. The argument should be in the form \[\[*CC*\]*YY*\] *MM**DD**hh**mm*\[.*SS*\] 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 60. 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. ## FILES - */usr/lib/cron/jobs* directory containing job files - */usr/lib/cron/spool* directory containing output spool files - */var/run/utmpx* login records - */usr/lib/cron/at.allow* allow permission control - */usr/lib/cron/at.deny* deny permission control - */usr/lib/cron/jobs/.lockfile* job-creation lock file ## SEE ALSO [nice(1)](/nice/1.md), [sh(1)](/sh/1.md), [umask(2)](/umask/2.md), [compat(5)](/compat/5.md), [atrun(8)](/atrun/8.md), [cron(8)](/cron/8.md), launchd(8), [sendmail(8)](/sendmail/8.md) ## 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.