You'd never get any work done if you typed every command that needs to be run on your CentOS system when it starts. Likewise, you could work more efficiently if you grouped together sets of commands that you run all the time. Shell scripts can handle these tasks.
A shell script is a group of commands, functions, variables, or just about anything else you can use from a shell. These items are typed into a plaintext file. That file can then be run as a command. CentOS uses system initialization shell scripts during system startup to run commands needed to get things going. You can create your own shell scripts to automate the tasks you need to do regularly.
This chapter provides a rudimentary overview of the inner workings of shell scripts and how they can be used. You learn how shell scripts are responsible for the messages that scroll by on the system console during booting and how simple scripts can be harnessed to a scheduling facility (such as
at) to simplify administrative tasks.
You also learn to fine-tune your machine to start at the most appropriate run level and to run only services you need. With that understanding, you'll be able to personalize your computer and cut down on the amount of time you spend repetitively typing the same commands.
Have you ever had a task that you needed to do over ...