topic Re: unset positional parameter in shell in Operating System - HP-UX

unset positional parameter in shell

support_billa — Tue, 27 Sep 2011 08:46:59 GMT

hello,

how can i unset positional parameter ?

unset a defined variable using the unset command:
unset variable_name

unset positional parameter ?

my proposal ? :

while [ $# -gt 0 ]
do
shift
done

test:

set a b c
$ echo "$*"
abc

#positional parameters $1, $2,$3

while [ $# -gt 0 ]
do
shift
done

echo "$*"

Re: unset positional parameter in shell

Matti_Kurkela — Tue, 27 Sep 2011 09:22:43 GMT

Your while-loop proposal can be simplified to:

shift $#

If you use the "set" command to set positional parameters, you should use "set -- <positional parameters>" to make sure you don't accidentally change any shell options.

An alternative way to unset all positional parameters would be:

set --

Re: unset positional parameter in shell

Dennis Handly — Tue, 27 Sep 2011 20:43:19 GMT

Typically you just use shift to march through your parms. You can use "set -A" to copy the parms to an array and then you can fiddle with that array. (Provided there are only 1023 parms.)

And then another "set -A" to restore the changed parms.

set -A SAVEARGS -- "$@"

The proper way to reset them is:
set -- "${SAVEARGS[@]}"

http://h30499.www3.hp.com/t5/Languages-and-Scripting/Shift-command/m-p/4133193