Given a file named "example"

which contains the line:

http://cisco.com You've got a match!

this:

#!/usr/local/bin/perl -w

use strict;

my $file = "/export/home/ssesar/example";
my $line;
open (FILE, $file) || die "\n$!";

while ($line = <FILE>) {
    chomp $line;
    if ($line  =~ m/^http\:\/\//) {
        print "line = $line\n";
    }
    else {
        print "Sorry, dude\n";
  }
}
[download]

works.