#!/usr/bin/perl

use File::Find;

my $old_flag = 0;

find (
  {
    wanted      => \&process,
    preprocess  => \&preprocess, 
    postprocess => \&postprocess
  }, 
  '/home/greg/mydir'
);

sub process {
  print "Processing\n";
  if (/.*\.old$/) {
    $old_flag = 1;
  }
}

sub preprocess {
  print "Pre-Processing\n";
  my @file_list = @_;
  $old_flag = 0;
  return @file_list;
}

sub postprocess {
  print "Post-Processing\n";
  my $old_CPB = "CPB.old";
  my $new_CPB = "CPB";

  if ($old_flag == 1) {
    if (rename $new_CPB, $old_CPB) {
      open IN, $old_CPB or die "Unable to open input CPB: $!";
      open OUT, ">$new_CPB" or die "Unable to open output CPB: $!";
      while (<IN>) {
        chomp;
        if (/^cat.*/) {
          print OUT "cat\t/kat/src/all/bld_pipe.4go \\\n";
          s/^cat\t/\t/;
        }
        print OUT "$_\n";
      }
    } else { #not found
      return;
    }
  }
  close IN;
  close OUT;
}