but is also the system of choice for old and exotic hardware that would be useless if Linux didn't exist.
Two years after Linus' post, there were 12000 Linux users. The project, popular with hobbyists, grew steadily,
all the while staying within the bounds of the POSIX standard. All the features of UNIX were added over the
next couple of years, resulting in the mature operating system Linux has become today. Linux is a full UNIX
clone, fit for use on workstations as well as on middle-range and high-end servers. Today, a lot of the
important players on the hard- and software market each have their team of Linux developers; at your local
dealer's you can even buy pre-installed Linux systems with official support - eventhough there is still a lot of
hard- and software that is not supported, too.
1.1.3. Current application of Linux systems
Today Linux has joined the desktop market. Linux developers concentrated on networking and services in the
beginning, and office applications have been the last barrier to be taken down. We don't like to admit that
Microsoft is ruling this market, so plenty of alternatives have been started over the last couple of years to
make Linux an acceptable choice as a workstation, providing an easy user interface and MS compatible office
applications like word processors, spreadsheets, presentations and the like.
On the server side, Linux is well-known as a stable and reliable platform, providing database and trading
services for companies like Amazon, the well-known online bookshop, US Post Office, the German army and
many others. Especially Internet providers and Internet service providers have grown fond of Linux as
firewall, proxy- and web server, and you will find a Linux box within reach of every UNIX system
administrator who appreciates a comfortable management station. Clusters of Linux machines are used in the
creation of movies such as "Titanic", "Shrek" and others. In post offices, they are the nerve centers that route
mail and in large search engine, clusters are used to perform internet searches.These are only a few of the
thousands of heavy-duty jobs that Linux is performing day-to-day across the world.
It is also worth to note that modern Linux not only runs on workstations, mid- and high-end servers, but also
on "gadgets" like PDA's, mobiles, a shipload of embedded applications and even on experimental
wristwatches. This makes Linux the only operating system in the world covering such a wide range of
hardware.
1.2. The user interface
1.2.1. Is Linux difficult?
Whether Linux is difficult to learn depends on the person you're asking. Experienced UNIX users will say no,
because Linux is an ideal operating system for power-users and programmers, because it has been and is being
developed by such people.
Everything a good programmer can wish for is available: compilers, libraries, development and debugging
tools. These packages come with every standard Linux distribution. The C-compiler is included for free - as
opposed to many UNIX distributions demanding licensing fees for this tool. All the documentation and
manuals are there, and examples are often included to help you get started in no time. It feels like UNIX and
switching between UNIX and Linux is a natural thing.
In the early days of Linux, being an expert was kind of required to start using the system. Those who mastered
Linux felt better than the rest of the "lusers" who hadn't seen the light yet. It was common practice to tell a
beginning user to "RTFM" (read the manuals). While the manuals were on every system, it was difficult to
Introduction to Linux
Chapter 1. What is Linux? 9