find duplicate line 1

[rozzay]

Hi I have a file that have thousands of lines I would like to create a perl script that looks at each and scan through to see if any of lines are duplicates. Any help or link is appreciated.

 

[KevinADC]

my %duplicates = ();
open (FH,'file.txt') or die "$!";
while (my $line = <FH>) {
   chomp($line);
   $duplicates{$line}++;
   if ($duplicates{$line} > 1) {
      print "This is a duplicate line: $line\n";
   }
}

The above will only tell you if the line is duplicated. I predict you will ask another question....