Sams Teach Yourself Shell Programming in 24 Hours, Second Edition

Special Variables

The shell defines several special variables that are relevant to option parsing and command execution. Table 13.1 describes all of these special variables.

Table 13.1. Special Shell Variables

Variable	Description
$0	The name of the command being executed. For shell scripts, this is the path which invoked it.
$n	These variables correspond to the arguments with which a script was invoked. Here n is a positive decimal number corresponding to the position of an argument (the first argument is $1, the second argument is $2, and so on).
$#	The number of arguments supplied to a script.
$*	All the arguments are double quoted. If a script receives two arguments, $* is equivalent to $1 $2.
$@	All the arguments are individually double quoted. ...