Shell Programming and Scripting

Hi,

I am new to unix and want to know what does the below code does in bash shell script...

ScriptCMD=$0
cd ${ScriptCMD%/*}
ScriptPath=`pwd`
ScriptName=${ScriptCMD##*/}
ScriptNoExtName=${ScriptName%.*}

Please explain me what are the values of the above five variables.
Also I would be very thankfull if you can provide good documentation on these concepts.

Help in this regard is highly appreciated.

Regards,
Azaz Ali.

Assume the script was called by :

Code:

$ /home/user/script.ksh

ScriptCMD=$0
The special variable $0 contains the name of the script specidied on the command line.
ScriptCMD=/home/user/script.ksh

cd ${ScriptCMD%/*}
The syntax ${var%pattern} substitute the variable $var and remove the smallest trailing part matching the pattern.
${ScriptCMD%/*}=/home/user

ScriptPath=`pwd`
Get the full script directory full path
ScriptPath=/home/user

ScriptName=${ScriptCMD##*/}
The syntax ${var##pattern} substitute the variable $var and remove the longuest leading part matching the pattern at the .
ScriptName=script.ksh

ScriptNoExtName=${ScriptName%.*}
ScriptNoExtName=script


I think that there is a little bug when setting the script path if the script path is not specied on the command line but found in the PATH by the shell.

Assume:

Code:

$ echo $PATH
....:/home/user/bin:...
$ cd /home/user
$ script.ksh          # the script is located in /home/user/bin

The execution of the script gives
ScriptCMD=$0 -> script.ksh
cd ${ScriptCMD%/*} -> cd script.ksh -> Execution ERROR
ScriptPath=`pwd` -> /home/user -> Invalid value !
ScriptName=${ScriptCMD##*/} -> script.ksh
ScriptNoExtName=${ScriptName%.*} -> script



Jean-Pierre.

Hi Jean,

Thank you very much for your detail explanation.

Regards,
Azaz Ali.