Programming

Working with Functions: Towers of Hanoi

For this article, I thought it would be beneficial to go back to some basics of shell scripting and look at how functions work. Most script writers probably eschew using functions because it's a bit antithetical to how scripts tend to evolve, as a sequence of commands on the command line that are captured in a file.

An Introduction to Tabled Logic Programming with Picat

Picat is a new logic-based programming language. In many ways, Picat is similar to Prolog, especially B-Prolog, but it has functions in addition to predicates, pattern-matching instead of unification in predicate heads, list comprehensions and optional destructive assignment. Knowing some Prolog helps when learning Picat but is by no means required.

Hash Tables—Theory and Practice

The first time I heard about hash tables was after taking a compilers course during my BSc. The truth is, I was not able to understand and appreciate their usefulness fully back then. Now that I know more about hash tables, I decided to write about them so others will see their importance as well.

Non-Linux FOSS: Code Your Way To Victory!

One of my favorite things about grade school was when the teacher would review for a test by playing Jeopardy. I'm pretty old, so my version of classroom Jeopardy was done on a chalkboard with the teacher reading answers from index cards, but the new computer-based versions I see in schools are at least as cool.

PHP for Non-Developers

After years of making it clear that I'm not a developer in just about every article I've written here at Linux Journal, I do have a confession to make. I can write the "Hello World" equivalent in almost every programming language out there. In assembly, it might have been "1+1", but my lack of advanced skills should be evident.

Picking Out the Nouns

A reader wrote a letter to me (oh happy day!), and although I'm still not entirely sure what she's trying to accomplish, it's an interesting puzzle to try to tackle anyway. Here's what she asked:

Non-Linux FOSS: .NET?

No, really! While on a normal day, the word "Microsoft" can be used as an antonym for "Open", the world of .NET seems to be going legitimately open source.

Days Between Dates: the Counting

In my last article, we began an exploration of date math by validating a given date specified by the user, then explored how GNU date offers some slick math capabilities, but has some inherent limitations, the most notable of which is that it isn't on 100% of all Linux and UNIX systems.

Days Between Dates?

Alert readers will know that I'm working on a major revision to my popular Wicked Cool Shell Scripts book to come out later this year. Although most of the scripts in this now ten-year-old book still are current and valuable, a few definitely are obsolete or have been supplanted by new technology or utilities. No worries—that's why I'm doing the update.

An Introduction to OpenGL Programming

OpenGL is a well-known standard for generating 3-D as well as 2-D graphics that is extremely powerful and has many capabilities. OpenGL is defined and released by the OpenGL Architecture Review Board (ARB). This article is a gentle introduction to OpenGL that will help you understand drawing using OpenGL.

Promise Theory—What Is It?

During the past 20 years, there has been a growing sense of inadequacy about the "command and control" model for managing IT systems. Years in front of the television with a remote control have left us hard pressed to think of any other way of making machines work for us.

Vagrant

How many times you have been hit by unit tests failing because of environment differences between you and other team members? How easy is it to build your project and have it ready for development? Vagrant provides a method for creating repeatable development environments across a range of operating systems for solving these problems.

Considering Legacy UNIX/Linux Issues

Gah, so frustrating! Ten years ago I wrote a rather popular book called Wicked Cool Shell Scripts, and I'm working on a new edition—a Tenth Anniversary release. There are lots of new scripts, entirely new chapters and updates to the older stuff.

Resizing Images with ImageMagick

Sure, you can open up a graphics program like GIMP and resize an image, but what if you want to resize 10, 50 or 200 images? ImageMagick's convert program is just what you need.

SciPY for Scientists

In my last article, I looked at NumPY and some of its uses in numerical simulations. Although NumPY does provide some really robust building blocks, it is a bit lacking in more sophisticated tools. SciPY is one of the many Python modules that build on NumPY's.

Numerical Python

For the past few months, I've been covering different software packages for scientific computations. For my next several articles, I'm going to be focusing on using Python to come up with your own algorithms for your scientific problems.

Alice, the Turtle of the Modern Age

Many of us grew up with LOGO, the kid-friendly programming language that guided a little turtle around a screen. Yes, it was simplistic. Yes, it taught only the very basics of programming concepts, but it also inspired an entire generation of programmers. The applications you run every day were written by people who steered a digital turtle around a screen in third grade.