Unix and Linux

COMP1260 > System Software

Introduction Unix is a computer operating system originally developed in 1969. It was first designed by AT&T employees working at Bell Labs and has since grown to be one of the most influential operating systems of all time. Currently Unix does not represent one single operating system. Instead, Unix is used as a base for many different operating systems. Systems that completely follow the standards set by Unix are called Unix systems. Operating systems that follow most but not all of the guidelines are called Unix-like operating systems. Most people ignore the difference between Unix and Unix-like operating systems and simply refer to both sets as Unix systems. Mac OSX 10.5 and Solaris are examples of Unix systems; Linux and BSD are Unix-like systems. Linux is one of the main Unix operating systems. Created in 1991 by Linus Torvalds, the operating system has become very well known in the server markets. The main reason that Linux has become so popular is that it is a secure, open source operating system. In addition, most variants of Linux are offered free of charge. Linux is currently in use in many different places such as cell phones, routers, servers, and supercomputers. Currently the University of Manitoba has both CentOS (Linux) and Solaris computers running on campus. The web server that is running this wiki is a Linux web server.

...by students I was incredibly relieved when I found the Linux and Solaris computers in the Engineering computer lab. They load up and run so much faster than the Windows computers. As well, because most people don't know what Unix is they simply avoid using these, which means they are always available to use. This made it much easier to quickly log on if I needed to do something fast then leave.

Uses

Ubuntu 8.10 Intrepid Ibex

What is Unix used for?

Unix systems offer the greatest flexibility of any operating system. Since Linux is open source, companies can take the computer code and adapt it to whatever needs they have. Due to this flexibility, Linux and Unix systems are used in everything from the most powerful supercomputers in the world to mobile phones and other embedded devices.

Unix has also gained popularity in the web server world. The advantage to using Unix web servers is that they almost never experience slow down or need to be restarted like Windows servers would. In fact, for most Unix web servers, hardware can be added or removed while the computer is running. This is very useful for companies, because having your website offline every time something must be changed can result in lost revenue. Currently, Unix is used for just over 50% of all the web servers in the world, compared to 30% for Windows.

Even more impressive is the use of Unix in supercomputers. Currently, 495 of the top 500 supercomputers in the world are running Unix, while the other 5 are running Windows. This means that 99% of the top supercomputers in the world are running Unix. The reason that Unix is chosen for supercomputers is because currently, only Unix has the tools for creating programs that can take full advantage of a supercomputers hardware.

Why should I use Unix?

There are many reasons to use a Unix operating system. Probably the greatest of these is that most distributions are offered free of charge. This means that you never have to pay to upgrade to a newer version. You can also try out different distributions without worrying about money. As well, most distributions have software repositories which are free of charge. These can include things like office suites, music players, dvd creation software, etc.

Another reason to use Unix systems is that they are very customizable. If you don't like the look of the operating system, you can change the theme of the desktop. You can also change the boot screen, the look of the login screen, the sound effects. If you feel particularly adventurous, you can change any of the underlying settings of the computer (Change how your printers work, what file manager you use, etc).

If you are interested in trying out Linux, most distributions will run off a live CD. This means that you can play around with the operating system without having to install anything.

Another option for testing is to use the free software Wubi. This software lets you install the Ubuntu Linux OS without having to go through any of the difficult procedures normally associated with installing a new operating system. If you don't end up liking Ubuntu, all you have to do is uninstall Wubi from Windows and Ubuntu will disappear without a trace.

Security

Is Unix secure?

Computer security is not absolute, and is therefore best represented as a continuum. By design, Unix is a very secure operating system, particularly when compared to Microsoft Windows. Throughout its existence, about 800 pieces of malware have been found for the Linux system. This pales in comparison to the approximately 11,000 pieces of malware found in the second half of 2005 for Windows. In addition, the comparatively small number of Linux users discourage targeting of the operating system.

In terms of security, one of the greatest advantages to using Unix is the fact that it makes use of root and regular user accounts. A root level account can change everything in the operating system. This allows a person to install software, delete critical system files, etc. However, by default Unix will never give the regular user root level access. This means that in the event that a virus got into the computer, it would only be able to access a few files (and not the files that keep the computer running). This concept has recently been added to Windows Vista, but tends to ask the user for access a little too often.

Distributions

What is a distribution?

For closed source operating systems like Microsoft Windows and Mac OSX there is essentially only one version of the operating system. Linux and Unix on the other hand are open source systems. Companies are free to view and change the Linux source code as they wish. This open source nature has thus created many different versions, or distributions of Linux.

Each Linux distribution is an operating system of its own. Distributions can look entirely different from one another, and at times even function differently than other versions. Some distributions come with nearly everything a user could need, while others are bare bones; meant for the user to choose every part of the operating system.

This variety of choices is one of the biggest bonuses to using Linux. There is a distribution that suits the needs of almost every user.

What distribution should I use?

With all of the different Linux distributions, it can be quite a daunting task choosing one to use. Some distributions even have unique, smaller versions of themselves, making it even more difficult to decide.

The most popular distribution of Linux is Ubuntu. Ubuntu first gained popularity by creating an easy to use operating system, with releases every six months. Ubuntu also has one of the strongest groups of users behind it. This has helped to create lots of documentation for the OS that new users will find very useful. If you are planning on trying out Linux, this is probably the best choice to start with.

Ubuntu isn't the only option when it comes to Linux. There are literally hundreds of different distributions (Red Hat, OpenSUSE, Mandriva, Fedora, and PCLinuxOS to name only a few). Each distribution offers its own take on how an OS should look, and philosophy on how certain things should be done. For a more complete list of Linux distributions see the wikipedia entry List of Linux Distributions.

References

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