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Comment of the Fortnight
10 August 1999
On-Line Tutorials

I've spent the past couple of weeks writing some on-line tutorials and cleaning up a Perl module. Here are the details.

The chmod Command

GNU/Linux uses the chmod command to let you change the access permissions for a file. For example, you can use this command so that anyone can read file sales.txt but only the owner can delete or upate it. This tutorial, which requires a 4.0 browser version or above, teaches you some of the features of this highly useful command.

This is not part of a larger series of Linux tutorials, unless there is some groundswell of demand for more installments. I wrote it mostly to get some more practice using style sheets and dynamic HTML. I also had an ulterior motive, which I may reveal at some later point, for writing this tutorial.

When Good Images Go Bad

I am both saddened and angered when I go to web pages that take forever to download what appear to be low-quality images. This situation is caused mostly when people make the wrong choice of image format and/or abuse the HTML command that's used to include an image on a web page. Here's a guide to help you avoid these errors.


Those of you who are Perl programmers may know about the Date::Calc module, which lets you do all sorts of useful calculations involving dates and times. This is an excellent module, written in a combination of the Perl and C languages.

I needed to use the module on a project a few months ago, but the project manager's Internet Service Provider wouldn't let users compile C programs. This meant I couldn't install Date::Calc on their system. I took the few functions that I needed and translated them to all Perl, and the project proceed nicely to its conclusion.

I decided that other people might be in a similar situation, so I translated the entire module to Perl only. You may see more details and download the module at this link. I also released the module through freshmeat.net, one of the web's better repository of UNIX and Linux utilities and programs.

Extra: Movie Review -- South Park

I saw “South Park” last weekend, a full-length movie based on the Comedy Central animated series. The plot includes a profanity-laced Canadian movie which causes a parents' group to declare war on Canada, which enables Satan and Saddam Hussein to return to earth. Only the students of South Park Elementary can save the day. This movie is R rated, and for good reason; the amount of vulgar language in this movie is truly staggering. Other than a couple of scenes which I found in truly poor taste, and incredibly uneven pacing, it's also very funny. The musical numbers (especially the one about Kyle's mother and the song where one character exhorts another to shut his mouth) are excellent indeed. If you are easily offended in any way, don't see the movie, and no, don't take any little kids to see it; it's totally inappropriate for that age group. By the way, be sure to stick around for the end credits; some of the names of the people doing voice characterizations will just blow you away.

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