Advanced Bash-Scripting Guide

# -a = all, -h = help, etc.if [ $# -ne $Number_of_expected_args ]thenecho "Usage: `basename $0` $script_parameters"# `basename $0` is the script's filename.exit $E_WRONG_ARGSfiMany times, you will write a script that carries out one particular task. The first script in this chapter isan example of this. Later, it might occur to you to generalize the script to do other, similar tasks.Replacing the literal ("hard-wired") constants by variables is a step in that direction, as is replacingrepetitive code blocks by functions.2.1. Invoking the scriptAdvanced Bash-Scripting GuideHaving written the script, you can invoke it by sh scriptname, [12] or alternatively bashscriptname. (Not recommended is using sh