Welcome to unix. A bit of convolution, but still far simpler than the Windows security model, IMO. (Though still not perfect, but I digress.)

First off, just because you can't log in as root doesn't mean you can't log in as root. ;-) It just means you can't log in via gdm (the GUI) as root - a good thing by any security-minded definition. You should be able to gain root access in any number of other ways, some requiring a password, others have the password as optional.

What I've done in the past is set up sudo to allow running of a particular command without a password. In my case, I want to run it as a particular user, so I have:

%build  ALL=(nobody)  NOPASSWD: /full/path/to/script
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# Are we the right user?
use User::pwent;
my $user_wanted = 'nobody';
my $user = getpwnam($user_wanted);

if ($< != $user->uid())
{
  exec(qw(sudo -u), $user_wanted, $0, @ARGV);
}
[...]
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Hope that helps.

See man 5 sudoers for a description of the configuration file syntax.

Any idea something like if i invoke my script with root privileges those privileges are inherited to commands in the script which avoids prompting of password each time

That's actually exactly what happens: if your script runs as root, anything it runs will also run as root. If you run your main script under sudo, it will run as root, so none of the commands it runs should need sudo to run.

chmod u+s script.pl
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