Comments on: How to schedule tasks on Linux using the 'at' command http://www.simplehelp.net/2009/05/04/how-to-schedule-tasks-on-linux-using-the-at-command/ Common questions, simple answers Sun, 22 Nov 2009 22:54:03 -0500 http://wordpress.org/?v=2.8.4 hourly 1 By: Use the At command in Linux for one-off task scheduling « Linux & Stuff http://www.simplehelp.net/2009/05/04/how-to-schedule-tasks-on-linux-using-the-at-command/comment-page-1/#comment-10708 Use the At command in Linux for one-off task scheduling « Linux & Stuff Sun, 24 May 2009 22:59:38 +0000 http://www.simplehelp.net/?p=2598#comment-10708 [...] in CLI | Tags: CLI The SimpleHelp blog has a nice post about this useful [...] [...] in CLI | Tags: CLI The SimpleHelp blog has a nice post about this useful [...]

]]> By: MikeT http://www.simplehelp.net/2009/05/04/how-to-schedule-tasks-on-linux-using-the-at-command/comment-page-1/#comment-10707 MikeT Mon, 04 May 2009 13:32:44 +0000 http://www.simplehelp.net/?p=2598#comment-10707 I have another followup for you on use of the at command. I've run into situations where I've needed a command run every hour <b>BUT</b> I needed the command to run <i>ONLY</i> if the previous run has completed. It might not be hung but it might be very very busy. I don't mind skipping an hour's execution if the process is still busy. When this situation arises, I don't use cron, I use 'at' and the last thing I put in my script is the at command itself to resubmit the job for execution. Now, even if the job takes three hours, at the top of the following hour, the at command will launch the job as expected without cron jobs bumping into each other. Yes, there's ways to put the logic into a script for cron to deal with it but that can also be difficult to maintain and not as obvious (to some) as this approach. I have another followup for you on use of the at command.

I’ve run into situations where I’ve needed a command run every hour BUT I needed the command to run ONLY if the previous run has completed. It might not be hung but it might be very very busy. I don’t mind skipping an hour’s execution if the process is still busy.

When this situation arises, I don’t use cron, I use ‘at’ and the last thing I put in my script is the at command itself to resubmit the job for execution.

Now, even if the job takes three hours, at the top of the following hour, the at command will launch the job as expected without cron jobs bumping into each other.

Yes, there’s ways to put the logic into a script for cron to deal with it but that can also be difficult to maintain and not as obvious (to some) as this approach.

]]> By: MikeT http://www.simplehelp.net/2009/05/04/how-to-schedule-tasks-on-linux-using-the-at-command/comment-page-1/#comment-10706 MikeT Mon, 04 May 2009 13:26:38 +0000 http://www.simplehelp.net/?p=2598#comment-10706 <i>If you don’t see atd running start it with this command: # /etc/init.d/atd start</i> More correctly, if it isn't running, it probably is not configured to startup when the system is restarted. Which may also keep the above command from working as expected. To correct this, use: <b><code> # chkconfig atd --level 234 on # service atd start </code></b> and check again to make sure it is running, if it is, continue with the instructions (which are very good BTW). If you don’t see atd running start it with this command:

# /etc/init.d/atd start

More correctly, if it isn’t running, it probably is not configured to startup when the system is restarted. Which may also keep the above command from working as expected. To correct this, use:

# chkconfig atd --level 234 on
# service atd start

and check again to make sure it is running, if it is, continue with the instructions (which are very good BTW).

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