topic Env Params in Operating System - HP-UX

Env Params

Shachar Twito_1 — Wed, 30 Jan 2002 11:47:48 GMT

I have a program that needs certain env params to run (for example in this question I'll use "path"). During installation, it adds a line to the .login file stating set path = ( /a/b /c/d $path ). The problem is that sometimes the path was already defined with the "/c/d" directories before that line, therefore the path value will be path=/a/b /c/d /c/d.
I don't want this duplicity (there's the length limit besides it's not nice...).
Any ideas how to solve this mess (on unix in general)?

Thanks,
Shachar

Re: Env Params

Ruediger Noack — Wed, 30 Jan 2002 12:03:16 GMT

Hi,

you can test if your env variable already contains the new value with a simple script like this:

ADDPATH=YES
for i in `echo $PATH | tr ':' ' '`
do
[ "$i" = "$NEWPATH" ] && ADDPATH=NO
done
[ "$ADDPATH" = "YES" ] && PATH=$PATH:$NEWPATH

Hope this helps

Ruediger

Re: Env Params

Robin Wakefield — Wed, 30 Jan 2002 12:19:58 GMT

Hi Shachar,

How about this:

if $a contains the directory you're interested in:

echo $path | tr ' ' '\012' | grep -q -x $a || set path = ( $path $a )

will only add $a if it's not already there.

Rgds, Robin

Re: Env Params

Shachar Twito_1 — Thu, 31 Jan 2002 08:19:05 GMT

Thank you all for the answers.
Robin,
Does this line will work in any shell (sh, sh, tcsh, ksh...), and will it work on sun?
Shachar

Re: Env Params

Robin Wakefield — Thu, 31 Jan 2002 09:00:48 GMT

Hi Shachar,

The example I gave was for a csh. For sh/ksh, you'll need something like:

echo $PATH | tr : '\012' | grep -q -x $a || PATH=$PATH:$a;export PATH

For Sun, you'll have to use /usr/xpg4/bin/grep, since this supports the -q/-x switches.

Rgds, Robin.