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Brief introduction to UNIX

Who Uses UNIX ?

UNIX is a very efficient, multi-user, multi-tasking operating system and is used particularly for database servers and Internet servers. Traditionally it has been used by large companies and educational establishments, but due to the popularity of Linux, it is now becoming more widely used.

It is scalable from a small system right up to a mainframe-class system (all you need to do is add extra hardware), which makes it suitable for anyone looking for a low cost, reliable operating system.

For programmers it has a wonderful set of built-in utilities, a programmable shell (command/user interface) and a straight forward structure that makes it very easy to quickly produce quite complex programs. The basics of using the shell are taught in our other UNIX tutorials including UNIX Fundamentals and Advanced UNIX Tools.

For end users, it has a friendly graphical interface (called X Windows) and many business applications and games.
UNIX Hardware Requirements

As it is very light on resource requirements it will run on 386 or 486 computers with 2Mb RAM and 40Mb of disk space. The GUI (X-WIndows) requires another 2Mb RAM. There is also a cut-down version which will run on a Psion 3a with 512kb RAM.
UNIX Performance Tuning

There are many kernel parameters which may need to be tweaked to run heavy duty applications such as Oracle (these will be specified in the installation guide), but generally they should be left alone.

To improve performance you need to know how the system is performing currently and which of the three main resources (cpu, memory, i/o) is under the most load.
UNIX provides many performance monitoring and statistics gathering tools which you can run to determine current loads and thus the limiting factor. Generally, though, in descending order of cost effectiveness, the things that you can do are:

* add more memory
* use a faster i/o bus technology (eg. SCSI instead of IDE)
* replace the cpu (the processor chip) with a faster one (eg Pentium III instead of a Pentium II). This may mean that the motherboard has to be replaced as well as all the memory chips.
* add a second processor. Again this may require a new motherboard and new memory chips
* schedule some jobs to run over night, or restrict access to certain applications (eg. games), if they consume a lot of resources un-necessarily.

UNIX Vendors

There are many commercial versions of UNIX from IBM, HP, Sun, Silicon Graphics, SCO, as well as several free versions – Linux, FreeBSD, NetBSD. Some of the commercial vendors are also starting to offer free/low cost versions, hoping to make their money from the sale of applications and/or support.
Advantages of UNIX

UNIX is widely supported, by many companies large and small and many recent graduates will have used it extensively during their courses. This means that there is a large pool of skilled resources able to provide help and support to anyone that needs it.

The other advantages already mentioned are that it is stable, scalable and makes efficient use of resources.
Disadvantages of UNIX

The one drawback with UNIX used to be that there weren’t many desktop or office applications available for it, but this is changing due to the popularity of Linux.