Line 17 looks like some part of your problem: If -- as appears from your use of qx() -- you're trying to use the system grep,

Use grep to search file

Search /etc/passwd for boo user:
$ grep boo /etc/passwd

You can force grep to ignore word case i.e match boo, Boo, BOO
and all other combination with -i option:
$ grep -i "boo" /etc/passwd

But, as is in your code, methinks the system will eat the $pattern.

once you solve passing the var, this may be helpful: another *nix grep discussion points out that...

-e PATTERN, --regexp=PATTERN    Use PATTERN as the pattern....

OTOH,you may find it useful (and more perl-ish) to user Perl's own grep which uses this syntax (from perldoc -f grep):

@foo = grep(!/^#/, @bar);    # weed out comments

In that case, I think you would do well to use qr at line 5.

Update: nobody home when the now-striken sentence was written. Echhh!