UNIX® Shells by Example, Third Edition

12.4. Positional Parameters and Command Line Arguments

12.4.1. Positional Parameters

Information can be passed into a script via the command line. Each word (separated by whitespace) following the scriptname is called an argument.

Command line arguments can be referenced in scripts with positional parameters; for example, $1 for the first argument, $2 for the second argument, $3 for the third argument, and so on. After $9, curly braces are used to keep the number as one number. For example, positional parameter 10 is referenced as ${10}. The $# variable is used to test for the number of parameters, and $* is used to display all of them. Positional parameters can be set or reset with the set command. When the set command is used, any positional ...