The Tie::File module can be used to bind an array to a file.
Any changes you make to the array are then made retrospectivly to the file, without having to load the file into memory.
This is especially useful for large files
ex.
#!/usr/bin/perl
use strict;
use Tie::File;
my @array;
my $filename = 'foo.dat';
tie @array, 'Tie::File', $filename or die "Error: Cannot open $filenam
+e\n";
push @array, "Hello, World!\n";