#!/usr/bin/perl -w

use strict;

$| = 1;

my $MAXVALUE = 0x30;

my $file = shift or die "Please name a file\n";

open my $fh, '<', $file or die "Can't open $file ($!)\n";
binmode $fh;
my $buffer;
CHUNK:
for (;;) {
    # Read as much as 8k, less if at end of file
    my $rc = sysread $fh, $buffer, 8192;
    die "Read error\n" unless defined $rc;
    # No more bytes?
    last CHUNK if $rc == 0;
    for my $byte (unpack('C*', $buffer)) {
        if ($byte > $MAXVALUE) {
            printf("%02x > %02x\n", $byte, $MAXVALUE);
            last CHUNK;
        }
    }
}
close $fh;