print &popline("passcodes.txt",10,7);
sub popline {
	my ($file, $lineswanted, $linelength) = @_;

	open 	DATA, "+< $file";
	my @fileinfo = stat DATA;
	my %records = ();
		$records{filesize} = $fileinfo[7];
		$records{wanted_bytes} = $lineswanted * $linelength;
		$records{readpoint} = $records{filesize} - $records{wanted_bytes};

	# seek (DATA, -$records{wanted_bytes},2); 	# reads from the end of file, readpoint computation not necessary
	seek (DATA, $records{readpoint},0);			# reads from beginning, used b/c readpoint computation needed for truncate

	my @lines = <DATA>;
	truncate(DATA,$records{readpoint});
	
	return @lines;
}