Things n' Stuff | Thoughts about the universe in general

Another article in the “I need to write this for myself and what better place then on my blog” series:

If you are familiar with the old (but great) Warcraft 2 game, then you know its a great multiplayer game but unfortunately you need a “Battle.net server” to play and even if the Blizzard servers were up (and for this old game, they’re not though there are a few 3rd party free servers) – you probably don’t want to have all the party goers connect up to an external server.

So how to run a Warcraft 2 LAN party?

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I’m using the current Ubuntu alpha – 11.04 as my desktop OS on my laptop, and on the same laptop I sometimes need to run VirtualBox to access an MS-Windows environment.

In the current Natty alpha this doesn’t work well. I have VirtualBox 4.0 installed from Oracle’s repository, but it doesn’t manage to compile the kernel module it needs – probably because of the “RC” nature of the current Natty’s kernel (2.6.38-rc4) as of this writing.

I’ve seen many posts on the internet about running Ubuntu 11.04 as a guest in VirtualBox, but couldn’t find anyone talking about my problem, which is the opposite – running VirtualBox on Ubuntu 11.04. So here’s how to get this thing working:

1. Install VirtualBox 4.0 (from Oracle’s repository)
2. Install the kernel headers package for Ubuntu: sudo apt-get install linux-headers
3. Edit the headers’ Makefile to declare the same version as the uname command: run uname -r and note the suffix after the version number, for example mine says “2.6.38-3-generic“, so I am interested in “-3-generic“. Edit the Makefile using sudo gedit /usr/src/linux-headers-<version>-3-generic/Makefile , and the fourth line should say something like “EXTRAVERSION = -rc4“. Change the value (in this case “-rc4“) to what you found out from uname.
4. add autoconf.h to the linux include directory, because it is missing for some reason:
   cd /usr/src/linux-headers-<version>-3-generic/include/linux
sudo ln -s ../generated/autoconf.h

Now you can run sudo /etc/init.d/vboxdrv setup and it should complete successfuly and allow you to start VirtualBox.

Related articles

• Ubuntu 11.04 “Natty Narhwal” Will Not Have A Release Candidate (digitizor.com)
• ‘Natty Narwhal’ Alpha Offers Peek at Ubuntu 11.04 (pcworld.com)

As system administrators we often want to list the last few lines from a log file in order to track problems and see system reports. The UNIX command tail is very useful for that purpose and lets you display an arbitrary number of lines from the bottom of any file.

But often this is not really what you want – an administrator might want to see what happens in the last X minutes and the common practice to do this is to run tail with a guessed number of lines, see if you get what you want and if its not enough increase the number and try again.

Here’s another approach that works well if the log file you want to trace has time stamps for its lines (more…)

Mozilla’s decision to offer users of Firefox 3.5 to automatically upgrade to 3.6 seems to be paying off quite well:

From looking at some web statistics that I generated from leading web sites, this is how the browser market place looks for the top 95% of web users:

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A chroot environment is simply a directory – inside which you can find a file system hierarchy exactly like your original operating system. You can then use the UNIX chroot command to open a shell in that directory so that command running under that shell see only the chroot environment and can’t mess up your system. This is very useful for many different reasons – for example if you want to build some software packages and you don’t want their build dependencies to pollute your real system.

Building a chroot environment is not difficult at all using the right tools, and YUM – the CentOS installation tool – has what you need.

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As we’ve know for quite a long time now, Ubuntu is aiming to look and behave as much like Mac as possible⁽1) – we’ve already seen the Growl-like on screen notifications (which are rather cool) and here is the next major user interface change:

In Ubuntu 10.04 – due to be released on late April of this year – the window buttons (close, maximize,minimize) will be on the left side of the window! See here for the branding screenshots.

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1. within 2 years Mark Shuttleworth said in 2008, so he’s clearly running out of time [↩]

Its time to update an old post about updates: Fedora 7 is again rather old, with the current Fedora being at 12, and 13 is right around the corner, but We’re still with CentOS 5 (I hear that RedHat is deep into beta with their next version – 6 but when it comes out is anyone’s guess).

In the mean time, if you want to run something a bit more modern maybe you’d want to upgrade your CentOS installation to Fedora 12 which can be considered pretty stable after a few months on the market. The reasons for the change may be numerous – maybe you need to run the latest subversion (with better merge tracking) or a new version of Ruby. Either way, if upgrading from CentOS 5 to Fedora 7 was a pain, guess how it is more the two years later?

Before we get to the action itself, I would be remiss if I would not recommend you to reconsider what you are about to do – this is a challenging exercise for many system admins and can sometimes end badly. I do not guarantee anything and if it breaks you get to keep both parts. Often its much faster and easier to just go to the server, stick a Fedora 12 DVD in the slot, reboot and let the DVD upgrade your system⁽¹⁾. That being said, this is fun if you’re into that sort of thing, so if you’re still with me, lets dive in!

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1. another safer options would be to upgrade to Fedora 7 using the instruction in the previous article linked above, and then use Fedora’s preupgrade tool to upgrade to Fedora 8, then to fedora 10, and from there to Fedora 12, though this procedure will also require physical access to the machine and multiple reboots and multiple long downloads [↩]

One of the most annoying issues with Linux’s graphical system (and any UN*X), is that if you have some keys setup for switching the keyboard layout – when using two or more keyboard layouts, such as for writing English and Hebrew – then that key combination cannot be used in any other keyboard shortcut.

Its most annoyingly present when setting the keyboard layout switching command to ALT+SHIFT (like in MS-Windows), then you can’t do any keyboard shortcut that has ALT+SHIFT in it – such as ALT+SHIFT+TAB to move to the previous window.

Well, finally there is a solution! As detailed in FreeDesktop.org’s Bugzilla and Ubuntu’s Launchpad , and thanks to Ilya Murav’jov we now have a patch to solve this ancient X11 problem.

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Here is another script I wrote for work and I thought it will be interesting enough to share:

Say you want to check which JAR files (or ZIP files for that matter, as Java ARchive files are just ZIP files with a different extension) contain files that contain some text. grep is the obvious answer, but how to grep files in JARs?

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