#!/usr/bin/perl -w
use strict;

$procfile2="data.txt";
open(PROC1,"$procfile2") or die "Can't open file $procfile2";
my @lines=<PROC1>;
close (PROC1);

my $nlines1=@lines;
my @proc_name1=();
for (my $i=0;$i<$nlines1;$i++)
   {
  if($lines[$i] =~ /(.*?)\s+(\S+)/)
 {
   $pp=$1;
   $pp1=$2;
    $length_pp = length($pp);
   $length_pp1 = length($pp1);
   if ($length_pp==15 || $lengt_pp1==10)
   {
     push(@proc_name1,$pp);
     }
   if ($length_pp==10 || $length_pp1==15)
   {
   push(@proc_name1,$pp1);
   }
 }
}
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Now as per your suggestion we have locatedlines having 15 charcaters. How do i look only the unique values as there may be same 15 character value repeated number of times.How do i pick up unique value of them. ? I found one such code in the web. Correct me if am wrong in my understanding of the code. Now to my understanding it empties a already existing hash seen and array uniq.we check the existence using unless.let me know how can i understand the sode below.

%seen = ();
 @uniq = ();
 foreach $item (@proc_name1) {
     unless ($seen{$item}) {
       $seen{$item} = 1;
       push (@uniq, $item);
    }
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