topic Re: Help need on perl scripting in Operating System - HP-UX

Help need on perl scripting

manoj_pu — Mon, 25 Jul 2005 09:48:36 GMT

Hello

Can any tell me how to execute two unix commands by using perl "exec()" function.

I want to execute below two commands in one shot.
1st Command is
DISPLAY=`/usr/bin/hostname`:10.0; export DISPLAY

2nd command is
/usr/bin/X11/mwm -display :10.0

Thanks & Regards
Manoj

Re: Help need on perl scripting

Rodney Hills — Mon, 25 Jul 2005 09:57:32 GMT

In perl it would be very similiar-

$display=`/usr/bin/hostname` . ":10.0";
system("DISPLAY='$display' ; /usr/bin/X11/mwm -display:10.0");

HTH

-- Rod Hills

Re: Help need on perl scripting

A. Clay Stephenson — Mon, 25 Jul 2005 09:58:42 GMT

This is not a valid use of the exec() function in Perl. Just like its C system call counterpart, exec() replaces the currently executing process and never returns so only the first exec() will ever be executed. You need to use the system() function instead which forks a child process to execute the command.

Re: Help need on perl scripting

Simon Hargrave — Mon, 25 Jul 2005 10:01:08 GMT

If you mean you want to run them one after the other but in one call to exec, then just chain them (like you have already chained DISPLAY= and export in the 1st "command"):

exec 'DISPLAY=`/usr/bin/hostname`:10.0; export DISPLAY ; /usr/bin/X11/mwm -display :10.0'

If you want to run them independantly in parallel, then there's no point. All your 1st command does is export a variable. Why do this if you're not going to use it, it'll disappear when you exit the exec anyhow.

Re: Help need on perl scripting

Simon Hargrave — Mon, 25 Jul 2005 10:05:01 GMT

Of course Rodney and Clay are correct in that you should use system() not exec()!

Re: Help need on perl scripting

manoj_pu — Mon, 25 Jul 2005 10:46:31 GMT

Thanks Everyone for the quick help.

Warm regards,

Manoj

Re: Help need on perl scripting

H.Merijn Brand (procura — Mon, 25 Jul 2005 11:09:11 GMT

And perl promotes the %ENV hash

use Sys::Hostname;
$ENV{DISPLAY}=hostname.":10.0";
system("/usr/bin/X11/mwm");

Enjoy, Have FUN! H.Merijn