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Linux is cool, Linux users know that much. There are a lot of cool things Linux, and to kick off, here is one of them: A linux beer machine.

The /proc/sys directory in the /proc virtual filesytem contains a lot of useful and interesting files and directories. Many kernel settings can be manipulated by writing to files in the proc filesystem. A lot of important information can be retrieved from these files. This is especially useful when you are troubleshooting or fine tuning your linux system. Following is a description of the most important files.

In my previous article I already touched on the subject of the virtual file-system mounted on /proc As this is an important topic on the LPI exam (and it's also a very interesting subject), we are going to explore the /proc file-system today.

The LPI certification is a valuable certification for Linux system administrators. LPI has partnered with Novell and now the certification has become even more valuable as it's also a Novell certification by now which means you get 2 certifications at once. The LPIC 1 certification is also the base for the ubuntu certified professional certification. So if you like to become a linux all-round certified administrator. This is probably one of the best (and cheapest) choices. This is the first article in a series of tutorials, which will try to help you prepare for the LPI certification exam.

The LPI certification is a great way to show you have Linux system administration knowledge. Especially when you don't haven working experience a certification is a valid tool to show you do have special knowledge about the operating system. The problem is the LPI didn't create the certification for people without experience. As a matter of fact, the exam is actually aimed at finding experienced administrators. That's why they have a lot of questions about stuff you don't encounter all the time, like little used options for command line arguments.

I like using Linux, it makes me feel secure. But there are still things even Linux users have to watch out for. I know Linux is much better than windows when it comes to security. But still sometimes I feel like we may feel to safe on our OS.

Dynamic checkbox creation I also created a box which contained checkboxes for a few of the options of the ls command. As I want to add more commands to the tool it would take me a lot of time to create all the checkboxes and a lot of copy pasting code. I don't think that's a good idea, so I've been thinking of some way of dynamically creating vertical boxes containing the checkboxes for all options per command. That way I can just create a VBOX by passing a command and it's options to a subroutine.

cheap Java hosting I've been hoping for a cheap Java hosting solution for years, as I feel Java programming is the most joyous experience. Especially thanks to the terrific API documentation. Today it was in the news google has added Java as a programming environment for it's app engine online application platform. And it is free, free within limits but it doesn't seem to me I'm going to get past their limits quickly as resources you can freely use are enough for 6 million monthly visits. If I get that kind of attention I will gladly pay the 10 cent a Gig transfer rate.

If you are looking for a hosting provider for your new website, or want to upgrade your hosting services your going to get confronted with a lot of options. It may not be completely clear what the differences are. No doubt you probably want some kind of Linux hosting as there are only very specific circumstances where windows web hosting has benefits. In my humble opinion you would only want windows hosting if you have a web service or application which can only be run on windows(which would be a design flaw). Reasons why Linux is superior for web hosting include:

A little sidestep from my learning of the Gtk toolkit for Perl GUI programming. I was thinking it would be nice to try some 2D animation on the desktop. Not the most useful thing maybe, but I like to make my learning process as much fun as possible. That keeps me motivated and happy. Custom windows It took me a lot of searching on the internet before I found a reasonably easy way to do this. The point is (or seems to be, I'm not an expert) that when I want to draw something to the Desktop with Gtk2 I always need to create a window (A square shaped window). I found out it's pretty easy to set the window decoration to false which provides me with a window consisting of a background alone. What I wanted though was some kind of invisible canvas on which I can draw an animation.

Getting together information The only problem I encountered at first is getting together the information to know exactly what to use and how to use it. I started by reading the sources for some programs I found on my system and debugging them to learn the way they are processed. This was a great learning experience, my knowledge has quickly expanded by doing this. Still there were some important things I really needed to help me trough the learning process. I needed good reference material, examples and a book. Sadly enough there doesn't seem to be any printed book about perl-Gtk, luckily I did find some great tutorials on the perl-Gtk site. I also found some other helpful tools and resources by accident.

So I thought of a reasonably trivial program I could write which would still be interesting enough and which can be build upon for a while to build some skill in perl GUI programming. I think it would be nice to be able to build a GUI for linux command line programs, that could have some value in the future. As that could quickly become to complex for my purpose and it would probably drive me to start messing with the code for the utility I want to write a GUI for, I chose instead to start writing a GUI for native built in shell commands.

Learning from other people's code The reason I want this debugging feature so hard is that I like to learn from other people's code. The thing I like so much about running an open source OS, is that I can just read the sources for programs on my system and try to figure out what they do and how they do it .

My choice has fallen on the Eclipse IDE, I know there are many good perl editors out there and I don't have any knowledge about which is the best choice for what job. I do know the choice of editor is very personal and there are even people who use vi as a Perl IDE. My main reason for using Eclipse is because I've read about it on a forum and many people seemed to like it (and it's free). It seems to be a bit of overkill to write my very simple pieces of code in a full fledged IDE and I know it has some downsides too.

I need to extend my programming knowledge, I know as a system administrator, I should automate everything I need to do more than twice and therefore I need more programming skills. I've been thinking of learning shell programming, as it is the most ubiquitous in Linux systems. I already know some shell programming and for most of the simple tasks I can easily write a small shell script. The problem is I really need more to become more skilled, to speed up the things I do and make my life easier.

In a previous article I discussed several ways to reset/recover/circumvent root password. While the article was written to assist people who have lost or forgotten a root password it was also a statement about security. As I was reading up on the subject I noticed there are some things I didn't know about, as my knowledge of the subject has aged a bit.

If you like me upgraded to ubuntu 9.04 jaunty jackalope changes are that you are confronted with a login screen at startup. Here's an easy way to get back your settings to login immediately. If you think this is a security risk, just read the article 10 ways of resetting a lost linux root password and think if you really need to protect against 4 year olds. If you really need security take appropriate measures. To me the login screen is only an annoyance. Here's how to remove it:

An update to my previous article My vi first steps I use vi instead of command line editors to do mass replacing of blocks and editing many files in the following way: say I know all files I need to edit in the current directory contain the text foo and the rest of the files don't. I open all files containing foo in vi:

I remember when I first started administrating Linux systems, I had to use the vi text editor to edit configuration files. My first encounters with vi were not of the pleasant kind. I hated vi, to me it felt completely counter intuitive with its command and editing mode. Which it apparently inherited from the days where terminals had few keys and didn't sport all the typewriter functions we have today. After a while of using vi I started to appreciate it's tremendous power. Nowadays I use it whenever I can. I must say vi has a steep learning curve but when you get past the first steps and have the feeling of the interface it's an incredible time-saver. It's comparable to the Linux command line interface, it takes a little while to learn but it's so efficient and powerful you get back the time you invested in learning a hundred fold.

A good password has the problem of being difficult to remember. And sometimes you might need to get in to a system where the root password is long forgotten (or left with the system administrator before you). Luckily there are ways of getting access to systems without having the password. This is of course in a sense also a security risk. That's why you should always be aware that having unattended physical access to a computer system means the same as having root access to the operating system. Unless the information on a system is encrypted, it's only as save as the room it's in.