The at utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-f file Specify the pathname of a file to be used as the source
of the at-job, instead of standard input.
-l (The letter ell.) Report all jobs scheduled for the
invoking user if no at_job_id operands are specified.
If at_job_ids are specified, report only information
for these jobs. The output shall be written to standard
output.
-m Send mail to the invoking user after the at-job has
run, announcing its completion. Standard output and
standard error produced by the at-job shall be mailed
to the user as well, unless redirected elsewhere. Mail
shall be sent even if the job produces no output.
If -m is not used, the job's standard output and
standard error shall be provided to the user by means
of mail, unless they are redirected elsewhere; if there
is no such output to provide, the implementation need
not notify the user of the job's completion.
-q queuename
Specify in which queue to schedule a job for
submission. When used with the -l option, limit the
search to that particular queue. By default, at-jobs
shall be scheduled in queue a. In contrast, queue b
shall be reserved for batch jobs; see batch. The
meanings of all other queuenames are implementation-
defined. If -q is specified along with either of the -t
time_arg or timespec arguments, the results are
unspecified.
-r Remove the jobs with the specified at_job_id operands
that were previously scheduled by the at utility.
-t time_arg
Submit the job to be run at the time specified by the
time option-argument, which the application shall
ensure has the format as specified by the touch -t time
utility.
