You can use the crontab to automate the running of scripts on your server. Cron is started automatically on entering multi-user run levels. To view your crontab, log in as the root user and run:

#crontab -l

The structure of the crontab entries is:

* * * * * command to be executed
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)

So for example:

* * * * * /sbin/ping -c 1 192.168.0.1 > /dev/null

This will ping 192.168.0.1 once each minute continuously. The > /dev/null portion redirects standard output to /dev/null so that the root user is only emailed if there is an error running the command. You can change this to > /dev/null 2>&1 to also trash error output.

To edit your crontab, run:
#crontab -e

Note: The text editor you use will be defined by the EDITOR variable. If you want to use a simple text editor, run the following command before editing the crontab:

# export EDITOR=nano

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