topic Script Help in Operating System - HP-UX

Script Help

Waqar Razi — Mon, 17 Nov 2008 15:11:43 GMT

Can some one help me understand the following script?

#-----------------
# functions
#-----------------
function Usage {
echo "\nUsage: $1 [ -h ] \n"
echo "where"
echo " -h = prints this message"
echo "example: $1 \n "
}
#-----------------

# Collect the input variables. Check to see if they are correct.

while getopts ":h" PARAMETER; do
case $PARAMETER in
h) # Need some help.
Usage $0
exit 1
;;
\?)
Usage $0
exit 1
;;
esac
done

# Cleanout the variable list
shift $(($OPTIND - 1))

This is in the beginning of the vg, lv creation scripts? Can some one please help me understand what this part of script does?

Re: Script Help

Dennis Handly — Mon, 17 Nov 2008 15:19:58 GMT

This script calls getopts(1) to crack the input line. It is looking for "-h" and invoking the help message in the function Usage.
Unrecognized options goto the "?" case.

After that is done, it shifts off the processed args, for OPTIND -1 args.

Re: Script Help

James R. Ferguson — Mon, 17 Nov 2008 15:24:27 GMT

Hi:

This is a standard way of processing commandline switches and arguments. In this case, only one optional switch ('-h') is allowed. Specifying '-h', or for that matter, any other flag or switch (an letter beginning with a hyphen) prints the name of the script and a usage message and then exits.

Regards!

...JRF...

Re: Script Help

James R. Ferguson — Mon, 17 Nov 2008 17:19:36 GMT

Hi (again):

By the way, in case it wasn't clear, Dennis pointed you to the manpages for 'getopts' and those for 'sh-posix':

http://docs.hp.com/en/B2355-60130/getopts.1.html

http://docs.hp.com/en/B2355-60130/sh-posix.1.html

On the shell manpage, see also the information about OPTARG, OPTERR and OPTIND.

Regards!

...JRF...