I have a script that reads STDIN by setting $/ to \16 and uses while (<>) to read 16 bytes at a time, then outputs the hex values of each byte. On MS-Dos based systems, it needs to read STDIN in binmode in order to represent the line-ends correctly. This works if the script is invoked with the < operator to feed the file in, or fed from a pipe, but if the file name is passed as a parameter, the (<>) magic does not respect the binmode setting.

This script is in a .cmd file so it can be invoked directly from the Command Prompt. Ignore everything up to the use strict; as this is a standard Perl/Batch polyglot. 

@rem = '--*-Perl-*--
@echo off
perl "%~dpnx0" %1 %2 %3 %4 %5 %6 %7 %8 %9
goto endofperl
@rem ';
#!perl
#line 8
use strict;
use warnings;

binmode(STDIN);
$/ = \16;
my $line = '';
my $len = 0;
my $offset=0;
my $offhex='';
my $ord=0;
my $hex='';
my $char='';
print <<HEAD;
Offset    00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F  0123456789A
+BCDEF
--------  -----------------------------------------------  -----------
+-----
HEAD
format STDOUT =
@<<<<<<<< @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< @<<<<<<<<<<
+<<<<<
$offhex,  $hex,                                            $char,
.
while (<>) {
  $len = length;
  $offhex = sprintf('%08X', $offset);
  $hex = '';
  $char = '';
  foreach (split (//)){
    $ord = ord($_);
    $hex  .= sprintf('%02X ', $ord);
    $char .= ($ord > 13 or $ord < 7) ? $_ : ".";
  }
  write;
  $offset += $len;
}
__END__
:endofperl

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Update: If I set the environment variable PERLIO=:raw as per ysth's suggestion, it works for files passed as parameters. This breaks redirected input, though! So, my script just tests %1 and only sets the PERLIO variable if there is a parameter.

In reply to binmode(STDIN) by PhilHibbs

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