I have a problem. I use program where i can create simple addons. Main program have a white list of function and for example i dont have permission to use "open" function

I will try something like this:

(...)
my @users = ();
open(FH,"/usr/bin/who|");
while(<FH>) {
   push @users,$1 if (/^(\w+)/);
}
close(FH);


if ( grep ( /$luser\b/, @users) ) {
 _take_actions();
}
(...)
[download]

But my code doesnt work. Of course i try use "system", "backticks", "exec" but without success.

How i can make "overloading" those function and execute "who" command? This white list is very simple. Main program looking only name of restricted commands. In white list i have only:

readline pack sleep time unpack sort

Sorry for my english skills.