Hi breezykatt,

Why twice?

Your first form won't work because each call to system spawns a new, independent shell.

Whether or not it's the best architecture for one script to call another under a different user is something I can't tell without knowing more about the problem you're trying to solve. But assuming you know what you're doing and why, this should work:

system("sudo -u newuser /path/to/file") == 0
    or die "system failed, \$?=$?";
[download]

Update: I believe the sudo equivalent of su - (aka su -l) is sudo -i, so if you need that, use sudo -iu newuser /path/to/file

Hope this helps,
-- Hauke D