What's the best/smartest way to grab lines from a file and discard them from the file after they've been used?

As already indicated by beable, here is good solution:

#!/usr/bin/perl -w 
###############################################
use strict;
use Tie::File;
my @ry=();

tie @ry,"Tie::File","file2use.txt" or die $!;

my $line = shift @ry;

untie @ry;
[download]

Viola! The top line will disappear.