Here's a less compicated way to do it.

use strict;
my $find = "word or string to find";
open FILE, "<searchfile.txt";
my @line = <FILE>;
print "Lined that matched $find\n";
for (@lines) {
    if ($_ =~ /$find/) {
        print "$_\n";
    }
}
[download]

However with this will not pick up a match that occurs over multiple lines, and it also is not very fast when munging through huge files.