18 Dec 08 Remembering The Shell’s Special Variables

I can never seem to remember what all of these default parameter variables are.  I found this small shell script that prints them out when I forget.

#!/bin/sh -vx
#######################################################
# example_1.1 (c) R.H.Reepe 1996 March 28 Version 1.0 #
#######################################################
echo "Script name is            [$0]"
echo "First Parameter is                [$1]"
echo "Second Parameter is               [$2]"
echo "This Process ID is                [$$]"
echo "This Parameter Count is   [$#]"
echo "All Parameters            [$@]"
echo "The FLAGS are                     [$-]"
It produces output like this:
#!/bin/sh -vx
#######################################################
# example_1.1 (c) R.H.Reepe 1996 March 28 Version 1.0 #
#######################################################
echo "Script name is            [$0]"
+ echo 'Script name is            [/home/me/bin/shellhelp]'
Script name is            [/home/me/bin/shellhelp]
echo "First Parameter is                [$1]"
+ echo 'First Parameter is                []'
First Parameter is                []
echo "Second Parameter is               [$2]"
+ echo 'Second Parameter is               []'
Second Parameter is               []
echo "This Process ID is                [$$]"
+ echo 'This Process ID is                [15190]'
This Process ID is                [15190]
echo "This Parameter Count is   [$#]"
+ echo 'This Parameter Count is   [0]'
This Parameter Count is   [0]
echo "All Parameters            [$@]"
+ echo 'All Parameters            []'
All Parameters            []
echo "The FLAGS are                     [$-]"
+ echo 'The FLAGS are                     [hvxB]'
The FLAGS are                     [hvxB]
via Richard’s Unix Shell Scripting Universe
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Tags: echo, parameter, Shell, variable
                                

                
Filed in CLI, Shell