Mmap allows you to treat a file as a scalar variable. There are caveats, from pod:

NAME
       Mmap - uses mmap to map in a file as a perl variable

SYNOPSIS
           use Mmap;

           mmap($foo, 0, PROT_READ, MAP_SHARED, FILEHANDLE) or die "mmap: $!";
           @tags = $foo =~ /<(.*?)>/g;
           munmap($foo) or die "munmap: $!";

           mmap($bar, 8192, PROT_READ|PROT_WRITE, MAP_SHARED, FILEHANDLE);
           substr($bar, 1024, 11) = "Hello world";

DESCRIPTION
       The Mmap module lets you use mmap to map in a file as a perl variable
       rather than reading the file into dynamically allocated memory. It
       depends on your operating system supporting UNIX or POSIX.1b mmap, of
       course. You need to be careful how you use such a variable...

After Compline,
Zaxo