Your tool has already been created on *nix (or cygwin). It's 'diff', 'diff' is an awsome little tool and fast. Just save the previous copy of what you want to compare to and 'diff prev_file current_file' It prints the differences between the 2.

If you want to persue the perl solution for academic reasons. Copy a previous file. Open the previous file and current file read them into arrays and compare the 2 arrays.

UNTESTED

#!/usr/bin/perl -w
use strict;

open (FH,"<prev_file") or die;
my @prev = <FH>;
close FH;

open (FH,"<current") or die;
my @current = <FH>;
close FH;

foreach (0 .. $#prev) {
    print $prev[$_] if ($prev[$_] ne $current[$_]);
}
[download]

Don't recreate a good wheel - apropos is your friend

grep

grep> cd pub grep> more beer [download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.