AT(1)

NAME
at - execute commands at a later time

SYNOPSIS
at time [ day ] [ file ]

DESCRIPTION
At squirrels away a copy of the named file (standard input default) to be used as input to sh(1) (or csh(1) if you normally use it) at a specified later time. A cd command to the current directory is inserted at the beginning, followed by assignments to all environment variables. When the script is run, it uses the user and group ID of the creator of the copy file.

The time is 1 to 4 digits, with an optional following `A', `P', `N' or `M' for AM, PM, noon or midnight. One and two digit numbers are taken to be hours, three and four digits to be hours and minutes. If no letters follow the digits, a 24 hour clock time is understood.

The optional day is either (1) a month name followed by a day number, or (2) a day of the week; if the word `week' follows invocation is moved seven days further off. Names of months and days may be recognizably truncated. Examples of legitimate commands are

    at 8am jan 24
    at 1530 fr week

At programs are executed by periodic execution of the command /usr/lib/atrun from cron(8). The granularity of at depends upon how often atrun is executed.

Standard output or error output is lost unless redirected.

FILES
/usr/lib/atrun    executor (run by
cron(8)).

in /usr/spool/at:
    yy.ddd.hhhh.*    activity for year yy, day dd, hour hhhh.
    lasttimedone    last hhhh
    past    activities in progress

SEE ALSO
calendar(1), pwd(1), sleep(1), cron(8)

DIAGNOSTICS
Complains about various syntax errors and times out of range.

BUGS
Due to the granularity of the execution of /usr/lib/atrun, there may be bugs in scheduling things almost exactly 24 hours into the future.

There is currently no way to delete a scheduled job. A workaround is to identify the correct file in /usr/spool/at and copy /dev/null on top of the file. Since the file is owned by the user that queued the job, it is possible to do this. Note that the file cannot be deleted due to the permissions on the /usr/spool/at directory.