Editing At (command) (section)

===Unix-like===
On Unix-like operating systems, <code>at</code> reads a series of commands from [[standard input]] and collects them into one "at-job" which is carried out at a later date. The job inherits the current environment, so that it is executed in the same [[working directory]] and with the same [[environment variable]]s set as when it was scheduled. It differs from <code>[[cron]]</code>, which is used for recurring executions (e.g. once an hour, every Tuesday, January 1 every year). As with <code>cron</code>, many Unix systems allow the administrator to restrict access to the <code>at</code> command. <code>at</code> can be made to mail a user when done carrying out a scheduled job, can use more than one [[job queue]], and can read a list of jobs to carry out from a [[computer file|file]] instead of standard input. The Linux <code>at</code> command was mostly written by Thomas Koenig.<ref>{{Cite web|url=https://linux.die.net/man/1/at|title=At(1) - Linux man page}}</ref>

The '''<code>{{visible anchor|batch}}</code>''' command can be used instead of {{code|at}} to only run scheduled jobs if the system's [[Load (computing)|load average]] is below a certain value.

====Examples====
A sample command to compile a [[C (programming language)|C]] program at 11:45 a.m. on January 31 would be:

<syntaxhighlight lang="console">
$ echo "cc -o foo foo.c" | at 1145 jan 31
</syntaxhighlight>
or
<syntaxhighlight lang="console">
$ at 1145 jan 31
at> cc -o foo foo.c
at> ^D #(press Control-D while at the beginning of a line)
</syntaxhighlight>

The '''<code>atq</code>''' program lists the currently queued jobs, while '''<code>atrm</code>''' removes jobs from the queue:
<syntaxhighlight lang="console">
$ atq
1234 2011-08-12 11:45 cc -o foo foo.c user
$ atrm 1234 
$ atq
$
</syntaxhighlight>

In some Unix-like computer [[operating system]]s, it uses a [[Daemon (computing)|daemon]], '''<code>atd</code>''', which waits in the background periodically checking the list of jobs to do and executing those at their scheduled time on behalf of '''<code>at</code>'''.