Thank you all for your precious help once again.

I´ve made the following code that works

use strict;
use warnings;

my $path='D:\npodev\forms\src';
my @intervalos= ("[a-e]", "[f-h]", "[i-m]", "[n]", "[o-s]", "[t-z]");
my $esquema="RMS_MC";
my $start_flag = '<REANALYZED>';
my $stop_flag = '</REANALYZED>';

sub procura_ficheiros{
  my ($path,$intervalo)=@_;
  opendir(DIR, $path) ||die "$!";
  my @files=grep{/^$intervalo.*\.[f|m]/i} readdir(DIR);
  closedir (DIR);
  my $aux=0;
  foreach my $pos (@files){
    $files[$aux]="\t\"".$path."\\".$files[$aux]."\""."   $esquema\n";
    $aux++;
  }
return @files;
}

foreach my $intervalo (@intervalos){
    my @ola=procura_ficheiros($path,$intervalo);
    my $replacement = join "", @ola;
    open ORIGINAL, "< teste.txt"
    or die "can't open original file\n";
    my $original;
    {
      local $/;
      $original = <ORIGINAL>;
    }
    close ORIGINAL;

    $original =~ s/
        $start_flag
        .*?
        (\s*)
        $stop_flag
        \n
        /$start_flag\n$replacement$1$stop_flag/gsx;

    open COPY, "> copy.txt"
    or die "can't write to copy\n";
    print COPY $original;
    close COPY;
    system "hello.bat";
}
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Thank you..