Linux Journal - HOWTOs

Hack and / - Message for You Sir

Kyle Rankin — Tue, 01 Dec 2009 08:00:00 +0000

It's easy to forget dæmons are there unless they demand your attention. A few years ago, I was walking through the expo floor at OSCON, when I noticed someone in a full BSD dæmon costume getting his picture taken with a few fans. When I saw them trying to figure out how to arrange everyone for the picture I couldn't help but yell, “No! The dæmon is always in the background!”

In case you

Playing with the Player Project

Kevin Sikorski — Tue, 01 Dec 2009 08:00:00 +0000

We've all heard that PC-based computers have increased in power and decreased in size, power consumption and cost. These improvements mean more people have access to them, but also that PCs are becoming more suited to being the brains of a mobile robot. It brings to robots a number of advantages, such as USB connectivity, greater memory capacity, more powerful processors and even allows for pl

Multisession Workstations

Jorge Salgado — Tue, 01 Dec 2009 08:00:00 +0000

The Linux Terminal Server Project (LTSP) has been around for years now, and it gets better with each new release. In the beginning, it was targeted at providing schools with a means to use low-cost computers as Linux terminal clients. It was a huge success; so much so, that LTSP now is included in several Linux distros, such as Edubuntu, as a regular package.

LTSP lets you tailor it to

Work the Shell - Calculating the Distance between Two Latitude/Longitude Points

Dave Taylor — Tue, 01 Dec 2009 08:00:00 +0000

Last month, I closed this column with a script that can return latitude/longitude values for two addresses, with the intent ultimately being to have the script calculate the distance between those two points. As an example:

$ farapart.sh "union station, denver co" \ "union station, chicago il" Calculating lat/long for union station, denver co = 39.75288,

Controlling the Humidity with an Embedded Linux System

Jeffrey Ramsey — Tue, 01 Dec 2009 08:00:00 +0000

Charles Darwin, in his Beagle Diary that led to the book Voyage of the Beagle, wrote while in Peru, “On the hills near Lima, at a height but little greater, the ground is carpeted with moss, and beds of beautiful yellow lilies, called Amancaes. This indicates a very much greater degree of humidity, than at a corresp

Use Linux as a SAN Provider

Michael Nugent — Sun, 01 Nov 2009 07:00:00 +0000

Storage Area Networks (SANs) are becoming commonplace in the industry. Once restricted to large data centers and Fortune 100 companies, this technology has dropped in price to the point that small startups are using them for centralized storage. The strict definition of a SAN is a set of storage devices that are accessible over the network at a block level. This differs from a Network Attached

Advanced Message Queuing Protocol (AMQP)

Joshua Kramer — Sun, 01 Nov 2009 07:00:00 +0000

What if, using a single service call, you easily could ask a computing cloud to give you the readings from thermometers in 100 different locations? Or, perhaps you'd like to know the status of the 89 servers under your control. In the past, you might have accomplished those things by writing a server dæmon. Your dæmon might have managed each of hundreds of connections, conducting specific oper

Work the Shell - Exploring Lat/Lon with Shell Scripts

Dave Taylor — Sun, 01 Nov 2009 07:00:00 +0000

With the rise of geolocation systems on mobile devices (think “around me” on the Apple iPhone), a consistent method of measuring points on Earth has become quite important. The standard that's used is latitude and longitude, which measure the distance north or south of the equator and the distance east or west of the prime meridian (which goes through Greenwich, England). Your GPS devices all

IPv4 Anycast with Linux and Quagga

Philip Martin — Sun, 01 Nov 2009 07:00:00 +0000

“DNS is down and nothing is working!” is not something anyone ever wants to hear at 3am. Virtually every service on a modern network depends on DNS to function. When DNS goes down, you can't send mail, you can't get to the Web, you can't do much—hopefully, your coffeemaker is not Web-enabled! Administrators do a lot of things to mitigate this risk. The traditional safeguard is to establi

Host Identity Protocol for Linux

Abhinav Pathak — Sun, 01 Nov 2009 07:00:00 +0000

An IP address determines the name and network location of a computer on the Internet. The network stack reuses this IP address at all layers, including the application layer. As a consequence, existing network connections break when an IP address changes. For example, suppose you are streaming a video from your favorite Web site and you switch from a WLAN to LAN connection. Then, your host's I