#! perl -slw
use strict;

my $bigstring;
open my $temp, '>', \$bigstring or die $!;
print $temp 'My oh so unique signature';
seek $temp, 2**19, 0;
print $temp chr(0);
close $temp;

print length $bigstring;

open $temp, '+<', \$bigstring or die $!;
seek $temp, 2**20, 0;
print $temp chr(0);
close $temp;

print length $bigstring;
print substr $bigstring, 0, 25;


__END__
c:\test>junk6
524290
1048578
My oh so unique signature


##</code><code>##

my $p = 0;
substr( $bigstring, $p, 4 ) = pack 'J', ..
$p += 4;

##</code><code>##

substr( $bigstring, $p+1 ) = '';