Close. 

if (!defined $foo_path) {
   print "\nFOO was not intended to run on OS:$^0\n"
   exit;
}

[download]

Or even better 

if (!defined $foo_path) {
   die "\nFOO was not intended to run on OS:$^0\n"
}

[download]

Ref: defined, die

Update: Fixed stupid mistake pointed out in MidLifeXis's reply.
Update: Sigh! Fixed the second snippet too.

In reply to Re: Using UNDEF by ikegami
in thread Using UNDEF by neo1491

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