Example 11-1. examples/regex/find_string.pl

#!/usr/bin/perl
use strict;
use warnings;

my $filename = shift or die "$0 FILENAME\n";
open my $fh, '<', $filename or die "Could not open '$filename'\n";

while (my $line = <$fh>) {
    if ($line =~ /REGEX/) {
        print $line;
    }
}