Shell scripts are an integral part of the Red Hat Linux system for configuring, booting, administering, and customizing Red Hat Linux. They are used to eliminate typing repetitive commands. They are frequently executed from the scheduling facilities within Red Hat Linux, allowing much flexibility in determining when and how often a process should run. And they control the start-up of most daemons and server processes at boot time.
The init daemon and its configuration file, /etc/inittab, also factor heavily in the initial start-up of your Red Hat Linux system. They implement the concept of run levels that is carried out by the shell scripts in /etc/rc.d/init.d, and they provide a means by which the machine can be shut down or rebooted in an orderly manner.
To have shell scripts configured to run on an ongoing basis, you can use the cron facility. Cron jobs can be added by editing cron files directly or by running commands such as at and batch to enter the commands to be run.