Functions in Shell Script

Shell function provides a way of mapping a name to a list of commands. Shell function can be compared with subroutines or procedures or functions of programming languages.

The main difference is that a new instance of the shell begins in order to run a shell script, whereas functions run in the current shell.

The following examples illustrate valid and invalid function definitions:

lsl() { ls -l ; } # valid lsl { ls -l ; } # invalid

Invoking a Function

To invoke a function, only its name is required, thus typing

$ lsl

on the command line executes the lsl() function, but typing

$ lsl()

does not work because sh interprets this as a redefinition of the function by the name lsl.

Happy Exploring!