Built-in variables are special variables provided to shell by Linux that can be used to make decisions within a shell program. You cannot modify the values of these variables within the shell program.
Some of these variables are
$# Number of positional parameters passed to the shell program
$? Completion code of the last command or shell program executed within the shell program (returned value)
$0 The name of the shell program
$* A single string of all arguments passed at the time of invocation of the shell program
To show these built-in variables in use, here is a sample program called mypgm2:
#my test program echo "Number of parameters is $#" echo "program name is $0"
echo "parameters as a single string is $*"
If you execute mypgm2 from the command line in pdksh and bash as follows,
$ bash mypgm2 Sanjiv Guha you get the following result:
Number of parameters is 2 Program name is mypgm2
Parameters as a single string is Sanjiv Guha
Was this article helpful?