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 ...

Get Ubuntu Unleashed 2014 Edition: Covering 13.10 and 14.04,Ninth Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.