Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

A Simple Example of a Positional Parameter

For example, if a shell program mypgm expects two parameters—such as a first name and a last name—you can invoke the shell program with only one parameter, the first name. However, you cannot invoke it with only the second parameter, the last name.

Here is a shell program called mypgm1, which takes only one parameter (a name) and displays it on the screen:

#!/bin/sh#Name display programif [ $# -eq 0 ] then   echo "Name not provided"else   echo "Your name is "$1fi

If you execute mypgm1, as follows

matthew@seymour:~$ bash mypgm1

you get the following output:

Name not provided

However, if you execute mypgm1, as follows

matthew@seymour:~$ bash  mypgm1 Heather

you get the this output:

Your name is Heather ...