Awesome timeline of Unix, Linux and Mac OSX

A beautifully constructed timeline of Unix which includes modern day Unix descendants such as Solaris and Mac OSX as well as Linux. This timeline is not very much unlike the mind map of Linux I had created a long time back. But this timeline also provides the year when the Unix/Linux flavor was born. [Via: Zwahlen Design blog]

Fig: Unix - Linux timeline

September to be one Ubuntu screencast per day month

September 2007 is going to be a special month for the Ubuntu enthusiasts and would be converts. In this month, you get to view videos of accomplishing various tasks in Ubuntu at the rate of one screencast per day.

Each screencast will be made available through the Ubuntu Screencast site in three sizes and two formats (OGG and Flash). The screencasts are licensed under the permissive Creative Commons Attribution-Share Alike 3.0 License, so you're free to modify, pass on, sell or otherwise distribute them so long as the attribution stays intact.

In fact, you do not have to wait for September to begin as the Ubunut screencast website already has a collection of videos which explain topics such as Samba file sharing, Printing in Ubuntu, Customizing Ubuntu desktop and many others as well.

So do check out the screencasts and bookmark the site as well for future reference.

Guess what this mystery character is used for ?

Today I came across an interesting blog post related to a mystery character. The character in question is the one shown below.

Fig: Picture of the mystery character.

Let's see what effect this mystery character has when it is cut and pasted in different text fields....

Fig: Firefox address bar

Fig: Pasted inside Gimp

As you can see, after this character is pasted, all the succeeding text is typed backwards from right to left. Really strange.

The closest valid explanation that was made was the following comment made by Charlie Halpern in the afore mentioned blog. And I quote ...

As noted about, the backwards type comes from the other characters, not from the circle of commas. The circle of commas (҉) is the Unicode character U+0489 COMBINING CYRILLIC MILLIONS SIGN. It actually is supposed to combine with the character before it, surrounding it with them crazy commas. It is a historic character that isn’t much in current use. See this pdf document for more details.

Note: For this unique magic to work, the program into which you paste this symbol should support unicode. For example, pasting this symbol in an 8-bit Ascii software such as Windows Notepad or Internet Explorer will display a series of gibberish.

Installing Solaris 10 on an under $300 machine

Solaris is perceived to be a heavy weight operating system in terms of the kind of resources (read hardware) that is required to install and use it. And when you hear the word Solaris, you at once visualize Sun Blades and Sun fire servers costing upwards of a few thousand dollars.

But it is possible to install Solaris 10 on a machine which costs under $300 if the machine is build with carefully chosen parts as shown by Christian Joaquin Cruz.

He selected parts with the following specifications to build his test machine :

• Motherboard - Intel D201GLY "Little Valley" Mini-ITX
• Hard drive - Maxtor 300GB PATA 16mb-buffer drive
• Memory - DDR 1GB pc6400 single-module 800MHz
• Optical drive - Sony DRU-170C
• Case - CoolerMaster Elite 340 mATX Case
• Power supply - RaidMaster 380w Power Supply
• Case fan - LD 80mm
  

And it cost him $279 before taxes. After installing Solaris 10 on this machine, he concludes ...

The machine, after installation of all the drivers, networking and apache configuration, was very functional and able to serve up web pages on my local network quite well. Secure Shell connections worked straight out-of-the-box, as did hot-plug-in detection of USB thumbdrives. The CD/DVD reader/burner was compatible with Solaris, but Sun has omitted the inclusion of a graphical CD/DVD burner application. The upshot of this is that you have to use the commands mkisofs and cdrw to use this functionality (or download a compatible GUI based application).

In most respects I am quite pleased at the results. It's quite a cool box for the very low amount of time and money invested.

Read the full findings of Christian Joaquin Cruz in taking his newly built under $300 Solaris box on a test drive. [Print version]

Tweak your host file to block ad generating web sites

Here is a cool tip to block ad generating websites from serving ads while you are browsing the web. The idea is to direct all the domains pointing to the ad serving sites to your localhost aka 127.0.0.1 . Now, the next time you visit a website and the website is serving an ad from a domain which you have directed to your localhost, you will see a blank space at the position where the ad was to be served.

This is done by inserting lines in your host file (/etc/hosts) on your Linux machine which are in the following format one domain per line :

FILE: /etc/hosts
127.0.0.1   localhost
127.0.0.1   ad.doubleclick.net
127.0.0.1   xx.adserver.xxx
...

... and so on.

One thing worth noting is that once you have collected (almost) all the ad serving sites domains, the resulting host file will be really huge as there are an ever growing collection of companies which make a living serving ads on publishing sites. More over, after some time it gets a bit tedious to update the /etc/hosts file on a regular basis.

LittleUbuntu has a nice writeup about implementing this feature in Ubuntu as well as a link to the original article.

Howto: Build an selinux policy the Red Hat enterprise way

Red Hat / Fedora has now got GUI tools to help edit and create SElinux policy files. And it is much more simpler to create a custom selinux policy in Red Hat Enterprise Linux.

In this detailed article, Dan Walsh gently walks you through the policy module creation process.

A lot of people think that building a new SELinux policy is magic, but magic tricks never seem quite as difficult once you know how they’re done. This article explains how to build a policy module and gives you the step-by-step process for using the tools to build your own.

Read more on a step by step guide to creating an selinux policy module explained by Dan Walsh.

Update: Also check out this PDF presentation on Managing Red Hat Enterprise Linux 5 which also contain information on SELinux.

Set up an Apache web server cluster in 5 easy steps

A server cluster is a group of independent servers that are managed as a single system for higher availability, easier manageability, and greater scalability.

In a Web server environment, server clusters can be defined in two basic ways:

Active/Active

• There are multiple independent, redundant servers
• The load is distributed through round-robin DNS
• The load is balanced by a load-balancing solution
  

Active/Passive

• Multiple servers are configured to provide a service
• Only a single server provides the service at any given time
• Other servers serve as hot-spares in case of a server (service) problem or a site hosted on the servers suddenly start getting load spikes such as when being slashdotted.
  

Now a days, many shared web hosting providers are turning to a web server cluster solution over managing individual web servers on independent machines. Clustering is said to provide some respite to the performance issues.

Eli M. Dow and Frank LeFevre, both, Software Engineers at IBM have written this insightful albeit rather technical article which explains how to setup an Apache web server cluster in 5 easy steps.

From the article ...

Spreading a workload across multiple processors, coupled with various software recovery techniques, provides a highly available environment and enhances overall RAS (Reliability, Availability, and Serviceability) of the environment. Benefits include faster recovery from unplanned outages, as well as minimal effects of planned outages on the end user.

To get the most out of this article, you should be familiar with Linux and basic networking, and you should have Apache servers already configured. Our examples are based on standard SUSE Linux Enterprise Server 10 (SLES10) installations, but savvy users of other distributions should be able to adapt the methods shown here.

Learn how to set up an Apache web server cluster in 5 easy steps.