#!/usr/bin/perl

# @(#) p1	Demonstrate linear sum of bytes in a file.
# This would show files being equal if the sums are the same.
# Adapted from the checksum fragment in "Programming perl, 3rd",
# page 821.

use warnings;
use strict;
use Carp;

my ($debug);
$debug = 0;
$debug = 1;

my ( $file, $sum );
foreach $file (@ARGV) {
  if ( !-f $file ) {
    print STDERR " Skipping $file, not a plain file.\n";
    next;
  }
  $sum = linear($file);
  print "$sum\t$file\n";
}

sub linear {
  my ($file) = $_[0];
  my ( $f, @sum );
  local $/;
  undef $/;
  open( $f, "<", $file ) || carp(" Ignoring file $file, cannot open.\n");
  $sum = unpack( "%C*", <$f> );
  close($f);
  return ($sum);
}

exit(0);

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0 
GNU bash 3.2.39
my-nl (local) 296
edges (local) 307
perl 5.10.0


==> data1 <==

  1 a
  2 b


==> data2 <==

  1 b
  2 a

data3:
     1	3 Musketeers
     2	5th Avenue
     3	100 Grand Bar
   ...
    27	Welch's Fudge
    28	York Peppermint Pattie
    29	Zagnut

data4:
     1	Oh Henry!
     2	GooGoo Supreme
     3	Forever Yours
   ...
    27	Mr. Goodbar
    28	Reggie Bar
    29	English Crunchie

data5:
     1	# Sun Nov 11 23:11:09 CST 2007
     2	# http://showcase.netins.net/web/creative/lincoln/speeches/cooper.htm
     3	# fmt -66
   ...
   826	the Government nor of dungeons to ourselves. LET US HAVE FAITH
   827	THAT RIGHT MAKES MIGHT, AND IN THAT FAITH, LET US, TO THE END,
   828	DARE TO DO OUR DUTY AS WE UNDERSTAND IT.

data6:
     1	
     2	
     3	
   ...
   826	you gain by forcing the sentiment which created it out of the
   827	you, who discarded the old policy of the fathers. We resisted,
   828	your political contests among yourselves, each faction charges

 Results:
215	data1
215	data2
27365	data3
27365	data4
17342	data5
17342	data6

ab
ba