Open System Services Shell and Utilities Reference Manual (G06.28+, H06.05+)

User Commands (a - b) at(1)
-s Requests that the Bourne shell be used for executing this job. In the current implemen-
tation, ksh will be used.
-t time Submits the job to be run at the specified time. The time argument must be in the for-
mat described for the touch command: [[cc]yy]MMddhhmm[.ss]. (For more informa-
tion, refer to the touch(1) reference page.)
-u user Deletes all jobs for the specified user. This flag must be used with the -r flag as fol-
lows:
at -r -u user
DESCRIPTION
The at command reads from the standard input file or accepts as arguments the names of com-
mands to be run at a later time. The at command allows you to specify when the commands are
to be run.
If a file specified on an at command line is executable (that is, has the x permission for the user
executing the command), at assumes that it is a command and that the job consists only of this
command. If the file is not executable, at assumes that you want its contents to be the instruc-
tions for the job (same as BSD at). If at cannot find the file at all, the specification is passed to
the date parser. If the specification is not recognized by the date parser, the user receives the
error message Unknown word.
Variables in the shell environment, the current directory, umask, and ulimit are retained when
the commands are run. Open file descriptors, traps, and priority are lost.
You can use at if your login name appears in the /usr/lib/cron/at.allow file. If that file does not
exist, at checks the /usr/lib/cron/at.deny file to determine if your login name is denied access to
at. The at.allow and at.deny files contain one login name per line.
If neither file exists, only a user with appropriate privileges can submit a job. If the at.allow file
does exist, the login name of a user with appropriate privileges must be included in it for that
user to be able to use the command.
Operands
when The required when operand can be one of the following:
• The at command recognizes a number followed by an optional suffix. at
interprets 1-digit and 2-digit numbers as hours. It interprets 4-digit
numbers as hours and minutes.
The LC_TIME environment variable specifies the order of hours and
minutes. The default order is the hour followed by the minute. You can
also separate hours and minutes with a : (colon). The default order is
hour:minute.
In addition, you can specify a suffixofam, pm,orutc. If you do not
specify am or pm, at uses a 24-hour clock. The suffix utc indicates that
the time is UTC (Coordinated Universal Time).
• The at command also recognizes the following keywords as special
times: noon, midnight, now, A for a.m., P for p.m., N for noon, and M
for midnight. The LC_TIME environment variable controls the addi-
tional keywords that at recognizes.
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