Hi there
I read carefully everybodys opinions and found the .. operator to be the simplest way to do it. Altough, I think I didn't express myself very well since your code (in general) is very complex on the regex side altough its valid it is not necessary for the simple thing I needed to to wich I paste bellow.

I abandoned the @array solutions because Im linking 1,2 - 1,3 giga files :)


Nevertheless I deeply thank you all for your fast replies and for sharing with me that bit of knowledge.

ps: I actually found fun in those while in while solutions :) geeee what a geek!

How it will stay

#!/usr/bin/perl

use warnings;
use strict;

#It needs ARGS and readable file
my $logfile=$ARGV[0];
my $contract=$ARGV[1];

unless (@ARGV == 2) {
     print "USAGE: $0 \"logfile\" \"numero\"\n";
     exit(1);
}

my $output="/tmp/session_".$contract.".txt";

unless (-e $logfile) {
 print "O ficheiro $logfile usado para input n\343o existe. Verifique 
+o nome do mesmo sff.\n";
 exit(1);
}

if (-e $output) {
  unlink($output);
}

open(OUTPUT,">>",$output) or die("Could not open conf file.");
open(LOG, $logfile) or die("Could not open conf file.");
while (<LOG>) {
 if (/:NOTICE:user=$contract,session=\d+:/ .. /\)\[/) {
  print OUTPUT $_
 }
}
close(LOG);
close(OUTPUT);
[download]

Actually I allready had acomplish that result using a marker with a var and is actually 7 seconds faster than the .. operator, but, I have deprecate it because is better coded with the above script (IMHO).

open(OUTPUT,">>",$output) or die("Could not open conf file.");
open(LOG, $logfile) or die("Could not open conf file.");
while (defined($line = <LOG>) ) {
 if ($line =~/:NOTICE:user=$contract,session=(\d+):/) {
  print OUTPUT $line;
  $echo=1;
 } elsif ($echo == 1) {
  print OUTPUT $line;
  if ($line =~/\)\[/) {
   $echo=0;
  }
 }
}
[download]