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Revision 7 as of 2007-12-09 22:44:21

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MemberManual / UsingCron

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 on Mire.

Requesting cron permissions

Use [https://members2.hcoop.net/portal/sec the security settings page] of the portal to request permission to use cron. You won't be able to create a crontab before submitting a request and having it approved.

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, run:

man 5 crontab

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

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 ~/scripts/clean-mail
11 0 * * 0   run-in-pagsh --fg ~/scripts/remove-tmp
12 0 * * 0   run-in-pagsh --fg ~/scripts/weekly-comment-check
*/10 * * * * run-in-pagsh --fg ~/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.