Okay, that's a start. What you're doing isn't technically wrong, but it's not very perl-ish. perl has a wonderful pattern matching facility; you may as well take advantage of it. If I'm understanding your problem, you could approach it like this:

if ($line =~ m/Trunk Group: (\w+)/) {
   my $match = $1;
   #do things with $match
}
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I suggest you do a 'perldoc perlre' and read up on regular expressions. I think you'll be pleasantly surprised by what you find there.