#!/usr/bin/perl -w

use strict;

my   $NEWLINE_SIZE  = length "\n";      # The size of the newline "character" in this OS
my   $OS_ADJUST          = 1;                # A way to somewhat generically do OS-specific offset computation

my   $KEY_OFFSET    = 'O';                        # Optimized key name for offset value
my   $KEY_LENGTH    = 'L';                        # Optimized key name for length value

my   $SEEK_SET = 0;                     # In case you don't want to export the constant for seek()

my   $Inpfnm = 'test2.dat';
my   $Wrkfnm = $Inpfnm . '-presort.dat';
my   $Srtfnm = $Inpfnm . '-sorted.dat';
my   $Outfnm = $Inpfnm . '-output.dat';

{
     &sortFile();
     &cleanUp();
}

exit;

sub sortFile
{
     # In the old days this would also be known as shakeTheHardDrive()
     open INPUT_FILE, '<', "$Inpfnm";
     binmode INPUT_FILE;

     open OUTPUT_FILE, ">$Outfnm";
     open SORTED_FILE, "<$Srtfnm";

     while (my $sortedKeyBuffer = <SORTED_FILE>)
     {
          chomp $sortedKeyBuffer;
          my ($keyValue, $inputOffset, $workingLength) = split /\|/, $sortedKeyBuffer;

          seek INPUT_FILE, $inputOffset, $SEEK_SET;
          my $inputBuffer = '';
          my $inputCount = read INPUT_FILE, $inputBuffer, $workingLength;
          print OUTPUT_FILE "$inputBuffer\n";
     }

     close SORTED_FILE;
     close OUTPUT_FILE;
     close INPUT_FILE;
}

sub cleanUp
{
     unlink $Wrkfnm;
     unlink $Srtfnm;
}

__END__