The Linux Command Line

Chapter 31. Flow Control: Branching with case

In this chapter, we will continue to look at flow control. In Chapter 28, we constructed some simple menus and built the logic used to act on a user’s selection. To do this, we used a series of if commands to identify which of the possible choices had been selected. This type of construct appears frequently in programs, so much so that many programming languages (including the shell) provide a flow-control mechanism for multiple-choice decisions.

case

The bash multiple-choice compound command is called case. It has the following syntax:

case word in
        [pattern [| pattern]...) commands ;;]...
esac

If we look at the read-menu program from Chapter 28, we see the logic used to act on a user’s selection

#!/bin/bash ...