How to set the display environment variable through a script?
i tried that using "setenv" but it gave me error.

is there any idea?

Try just typing env. If that doesn't work, try just typing set. Now, if that doesn't work, I'm out of ideas...

in script,
you can add following line;

export DISPLAY=`uname -n`:0.0

It depends what shell you are
using. For example:

C Shell: setenv DISPLAY some_host:0.0
Bourne Shell: DISPLAY=some_host:0.0; export DISPLAY
Korn Shell: export DISPLAY=some_host:0.0
BASH: export DISPLAY=some_host:0.0

...where "some_host" is the hostname or IP
address of the X workstation or console you
are using.

Since you said you tried "setenv", I assume you
are using "csh". You may also want to check the
man page for csh and the "source" command if you
want the setting to be persistant in your
current session's environment.

to be clear..
while in the normal command mode i use

setenv DISPLAY system-no:0.0
and that works fine.

if i use the same in script.. then it gives me errors like

setenv: command not found

is there any remedy?

First... are you using csh?
Can you verify this the shell you are using?
If so, setenv is a built-in so I'm not sure why you
would get that particular error.

Can you supply more info. (maybe even the script)?

Also, it has been said the csh is not a good shell for
scripting for various reasons but an interesting (amusing)
article by Tom Christiansen discusses the "cons"...
Now while i agree with Tom, I would not begrudge
anyone the freedom to "find out for themselves"

http://www.dubois.ws/software/csh-tcsh-book/csh-whynot

yes i am using a csh.
the script i have used is the following.

setenv DISPLAY 172.24.1.55:0.0
/opt/netscape/netscape&

it invokes netscape if i have already set display.
but the first line gives me error.