at Command Syntax

Example Meaning
at noon 12:00 PM September 18, 2001
at midnight 12:00 AM September 19, 2001
at teatime 4:00 PM September 18, 2001
at tomorrow 10:00 AM September 19, 2001
at noon tomorrow 12:00 PM September 19, 2001
at next week 10:00 AM September 25, 2001
at next monday 10:00 AM September 24, 2001
at fri 10:00 AM September 21, 2001
at OCT 10:00 AM October 18, 2001
at 9:00 AM 9:00 AM September 19, 2001
at 2:30 PM 2:30 PM September 18, 2001
at 1430 2:30 PM September 18, 2001
at 2:30 PM tomorrow 2:30 PM September 19, 2001
at 2:30 PM next month 2:30 PM October 18, 2001
at 2:30 PM Fri 2:30 PM September 21, 2001
at 2:30 PM 9/21 2:30 PM September 21, 2001
at 2:30 PM Sept 21 2:30 PM September 21, 2001
at 2:30 PM 9/21/2010 2:30 PM September 21, 2010
at 2:30 PM 21.9.10 2:30 PM September 21, 2010
at now + 30 minutes 10:30 AM September 18, 2001
at now + 1 hour 11:00 AM September 18, 2001
at now + 2 days 10:00 AM September 20, 2001
at 4 PM + 2 days 4:00 PM September 20, 2001
at now + 3 weeks 10:00 AM October 9, 2001
at now + 4 months 10:00 AM January 18, 2002
at now + 5 years 10:00 AM September 18, 2007

ACL

This is controlled by a pair of files called at.allow and at.deny.  The location and even the exact use of these files vary from system to system.  For Linux these file exists in /etc.  On Linux:

  • If neither file exists then only the user root can use the at command.
  • If only at.deny exists, then any user except those listed in this file can use the at command.
  • If at.allow exists then only users listed in this file can use the at command.  Note if this file exists then any at.deny file is ignored.

To see a list of pending at jobs (the ones that haven’t run yet), use the command “atq“.  This will show the job number and date-time for that job.

To see the contents of some at job, use the command “at -c jobnum“.  This shows the complete environment that gets set for the job as well; the actual commands of your job are at the bottom.

To delete an at job before it has run, use the command atrm jobnum“.

An at job may be created in a particular queue, using the form “at -q queue date-time“.  The queue is a single letter.  The default queue is “a“.  Queue “b” is reserved for batch jobs.  Using higher lettered queues will run your at job with higher nice values.

Leave a Reply

Your email address will not be published. Required fields are marked *