HOW-TOs

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.

Synchronize Your Life with ownCloud

Like most families these days, our family is extremely busy. We have four boys who have activities and appointments. My wife and I both have our own businesses as well as outside activities. For years, we've been using eGroupware to help coordinate our schedules and manage contacts. The eGroupware system has served us well for a long time. However, it is starting to show its age.

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.

Easy Watermarking with ImageMagick

Let's start with some homework. Go to Google (or Bing) and search for "privacy is dead, get over it". I first heard this from Bill Joy, cofounder of Sun Microsystems, but it's attributed to a number of tech folk, and there's an element of truth to it. Put something on-line and it's in the wild, however much you'd prefer to keep it under control.

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.

Encrypt Your Dog (Mutt and GPG)

I have been focusing a lot on security and privacy issues in this year's columns so far, but I realize some of you may expect a different kind of topic from me (or maybe are just tired of all this security talk). Well, you are in luck.

Open Axiom

Several computer algebra systems are available to Linux users. I even have looked at a few of them in this column, but for this issue, I discuss OpenAxiom. OpenAxiom actually is a fork of Axiom. Axiom originally was developed at IBM under the name ScratchPad. Development started in 1971, so Axiom is as old as I am, and almost as smart.

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.

Security Hardening with Ansible

Ansible is an open-source automation tool developed and released by Michael DeHaan and others in 2012. DeHaan calls it a "general-purpose automation pipeline" (see Resources for a link to the article "Ansible's Architecture: Beyond Configuration Management").

Tails above the Rest, Part III

In my first two columns in this series, I gave an overview of Tails, including how to get the distribution securely, and once you have it, how to use some of the basic tools.

rc.local, Cron Style

Occasionally as seasoned Linux users, we run across simple things we never knew existed—and are amazed. Whether it's tab autocompletion, sudo !! for when you forgot to type sudo or even recursive file listing with ls, the smallest tricks can be so incredibly useful. Not long ago, I had one of those moments.

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.

A Little GUI for Your CLI

I've tried pretty much every IRC client available for both Linux and OS X. (I use both platforms during my day job.) No matter how many times I try to find a GUI application that meets my needs, I always turn back to Irssi.

TogetherJS

Want to add real-time collaboration to your Web application? Mozilla's TogetherJS is worth a look.

Command-Line Cloud: rss2email

In my last article, I started a series called Command-Line Cloud. The intent of the series is to discuss how to use the cloud services we are faced with these days without resorting to a Web browser. I spend most of my time on the command line, so that's where I'd most like to interface with cloud services.

Two-Factor Authentication System for Apache and SSH

If you run a publicly accessible Web server for your own use (and let's face it, if you're reading Linux Journal, there's a very good chance you do), how do you go about limiting the risk of someone accessing your site and doing bad things? How about SSH, an even bigger concern?