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This page describes the basic use of cron on HCoop systems.

<<TableOfContents>>

= Prerequisites =

It is very important that you read the [[MemberManual/RunningUnattendedCommands|Running Unattended Commands page]] to understand the general idea of how to run unattended commands.

= Making a cron configuration file =

Cron needs a special configuration file to tell it how to operate.  It is suggested that this file be called {{{~/.crontab}}}, though it can have any name.

For an explanation of the format of this file, see the [[http://linux.die.net/man/1/crontab|crontab manual page]] (or run `man crontab` on the shell server).

= Managing your cron jobs =

== Activating your cron configuration ==

Once you are satisfied with your setup, run the following command to activate your changes, assuming that your configuration file is called {{{~/.crontab}}}:

{{{
crontab ~/.crontab
}}}

== Disabling your cron jobs ==

Just run `crontab -r ~/.crontab`

== Checking your cron configuration ==

Run `crontab -l` to display the jobs cron is running for you.

= Examples =

One convention for making scripts to run commands in their own PAG, as specified by the [[MemberManual/RunningUnattendedCommands|Running Unattended Commands page]], is to create the {{{~/scripts}}} directory, and place your scripts there.  Then, make a cron configuration file that looks something like this.

{{{
PATH=/afs/hcoop.net/common/bin:/usr/local/bin:/usr/bin:/bin

09 0 * * 0   run-in-pagsh --fg clean-mail           ~/scripts/clean-mail
11 0 * * 0   run-in-pagsh --fg remove-tmp           ~/scripts/remove-tmp
12 0 * * 0   run-in-pagsh --fg weekly-comment-check ~/scripts/weekly-comment-check
*/10 * * * * run-in-pagsh --fg make-git-projects    ~/scripts/make-git-projects
}}}

The PATH line is needed so that you have access to {{{run-in-pagsh}}}.  Make sure you don't try to reference any other environment variables like {{{$HOME}}}, because cron will not expand them properly.

The first cron command runs something 9 minutes after midnight (aka the "0th" hour), every day of the month, every month, provided that it is Sunday (aka the "0th" day of the week).  In short: run something at 12:09 every Sunday.

The second and third commands are similar.

The fourth command runs something every 10 minutes.
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CategoryMemberManual