While the Linux variant of UNIX is fast becoming a desktop operating system, UNIX’s multiuser capabilities make it ideally suitable in a server role.

When tasked as a web or database server, a properly configured UNIX system will provide unparalleled periods of uptime, requiring little service. The structure of UNIX means that in the case of a hardware failure, sections of a data structure can be taken offline, replaced and put online again without shutting down the system. This makes UNIX a good choice for mission critical applications.

UNIX’s multi-user capabilities make it highly resistant to attack. It’s designed in such a way that even if a malicious party did gain access to the system, their activities would be restricted to the user account they had access to, leaving them unable to damage critical system resources.

For this reason, there are very few viruses that target UNIX systems, and even fewer that pose any real threat. In fact, most UNIX virus scanners, for example, those running on mail servers – do most of their work removing viruses intended for other operating systems, to which they are immune.

UNIX is also long term cost effective; because by design it’s independent of the hardware it runs on. It will obviously run faster on more powerful hardware, but it does not require powerful hardware to begin with, so existing computers in your network rarely become obsolete.

Which Unix to use
Brand names aside, UNIX comes in two main variants: commercial distributions and open source distributions. Each has it’s own distinct features and advantages that need to be carefully considered when choosing which product is right for you.

Commercial UNIX
Commercial UNIX has the distinct advantage of having IT vendor’s support. When something goes wrong in the system, there’s usually someone you can call that will help you with the problem you’re having.

Commercial distributions often adhere to established standards, so chances are high that the software you need will run reliably on your system. Commercial UNIX often utilizes proprietary code to ensure that the system is as stable as possible.

Some distributors write commercial UNIX specifically for a particular set of hardware. Examples of this include Sun’s Solaris for their SPARC range, and IBM’s AIX for their pSeries. The advantage of this approach is that the software can be highly optimized for
that hardware, giving maximum performance and a greater level of stability.

Using commercial UNIX with proprietary code does mean that the software will be guaranteed scalable, but it also means you may be locked into a particular upgrade path and can only use hardware from one specific company.

Open Source UNIX
Open source UNIX is a hotbed of emerging technology. Because the code is open and available, you can compile UNIX for just about any hardware. It is free, because open source UNIX is distributed under the GNU General Public License (GPL).

The GPL allows you to make any modifications you see fit to the code in order to improve on any system component, provided you make your changes available to the rest of the open source community under the same license, and provide them with the modified source. GPL software has no warranty of any kind.

FreeBSD, a widely used open source UNIX, works a little differently. The bulk of its code is covered by the GPL, but FreeBSD incorporates functionality from several proprietary modules, including some from the original version of BSD. So FreeBSD is covered by the GNU GPL, the BSD copyright, and has restrictions on the redistribution of several proprietary components. Ultimately this makes FreeBSD a bit of a hybrid.
One of the fastest growing UNIX variants is Linux, the UNIX-clone created by Linus Torvalds. It is particularly interesting in that it has been ported to many different platforms, from desktop machines to PDAs and mobile phones. With the arrival of UNIX desktops, such as Gnome and KDE, Linux has started to make inroads in the desktop computing market as well.

You can download open source versions of UNIX, including FreeBSD and Linux, without paying for them. But because of the terms of the GPL, you usually cannot get support for such distributions.

However, because of the wide user base, you can get support for open source UNIXes by turning to the Web, where there is a wealth of documentation and user group expertise to draw from. Alternatively, you can choose to buy commercial support from a company that
specializes in supporting open source UNIX.

Also, the flexibility to compile code for any processor doesn’t guarantee that the software will be compatible with other hardware in your system, such as the particular brand of graphics card or network hub you have. However, if you search the Internet you will often find that there is a driver project underway by others who have encountered the same difficulty.

After get known on which UNIX to choose, commercial UNIX, and open source UNIX, will talk about “Brands of commercial UNIX“, “Brands of open source UNIX” on How to Choose Unix [Part 2]