LPI Linux Certification in a Nutshell, 2nd Edition

Objective 2: Customize or Write Simple Scripts

You've seen how the use of bash configuration files, aliases, functions, variables, and key bindings can customize and make interaction with your Linux system efficient. The next step in your relationship with the shell is to use its natural programming capability, or scripting language. The scripting language of the original Bourne shell is found throughout a Linux system, and bash is fully compatible with it. This section covers essential bash scripting language concepts as required for Exam 102.

In order to have a full appreciation of shell scripting on Linux, it's important to look at your Linux system as a collection of unique and powerful tools. Each of the commands available on your Linux system, along with those you create yourself, has some special capability. Bringing these capabilities together to solve problems is among the basic philosophies of the Unix world.

Script Files

Just as the configuration files discussed in the last section are plain text files, so are the scripts for your shell. In addition, unlike compiled languages such as C or Pascal, no compilation of a shell program is necessary before it is executed. You can use any editor to create script files, and you'll find that many scripts you write are portable from Linux to other Unix systems.

Creating a simple bash script

The simplest scripts are those that simply string together some basic commands and perhaps do something useful with the output. Of course, this ...