#!/usr/bin/perlopen(SIG, $ARGV[0]) || die "open $ARGV[0]: $!";$n = sysread(SIG, $buf, 1000);if($n > 510){  print STDERR "boot block too large: $n bytes (max 510)\n";  exit 1;}print STDERR "boot block is $n bytes (max 510)\n";$buf .= "\0" x (510-$n);$buf .= "\x55\xAA";open(SIG, ">$ARGV[0]") || die "open >$ARGV[0]: $!";print SIG $buf;close SIG;