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LINUX - What is Linux

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What is Linux?




  1. Brief Introduction
  2. Screenshots
  3. Specifications
  4. Supported Platforms
  5. Requirements
  6. Who's using it?
  7. Why using it?
  8. Where to get help
  9. Software

Brief Introduction

Linux is a highly stable, very fast, fully-fledged unix-type operating system, programmed by a community of thousands of people on the internet. It is distributed by the terms of the GNU Public License, which means it is free. It is used by several million people, organizations and companies world-wide (see also The Linux Counter).

That's "just" the kernel. A kernel is a piece of software, which controls the way, in which the hardware and the software communicate. Easy enough, right? Wrong. This is a rather complex task. Every OS (Operating System), has a kernel. It is, however, quite unusual to name the OS after the kernel.
Operating System
The kernel by itself is of no use to (nearly) anybody. In order to be usable, an OS needs some more essential programs. The program "init" for instance is very important, since the system won't be able to boot up without it.
While it is perfectly possible to use a Linux-system without a GUI (graphical user interface), few want to miss its comfort. Today, most GUIs are seamlessly integrated with the OS. Still, the GUI is not part of the OS, but a program by itself. On Linux, as on almost every Unix, this is the X-Server aka X Windowing System aka X11.
To actually use the system for anything else then tinkering around, you need applications. Those are, for instance, text processors, web browsers, book keeping software, games, graphic programs, audio editors, etc., etc.
Take all of the above together, and you get a distribution. Linux distributors are independent organisations, who basicly collect software for Linux and, well, distribute it. More about different distributions.


Since a lot of screenshots need a lot of space and a lot of bandwidth, we put them on a different page.


Supported Platforms

  • Either 32 or 64 bit, depending on architecture.
  • Multitasking: several programs running at once.
  • Multiuser: several users working on the same machine at once.
  • Multiplatform: runs on many different CPUs.
  • Multiprocessing: SMP for up to 16 processors.
  • Clustering: Clusters up to an unknown size (520 machines work already).
  • Memory protection so a process can't bring the whole system down.
  • Load on demand executables: only those parts of a program which are really needed are being loaded.
  • Virtual memory using paging (only parts of processes get swapped out on disk)
  • A unified memory pool for user programs and disk cache, so that all free memory can be used for caching.
  • Dynamically linked shared libraries (DLL's). Static libraries too, of course.
  • For the most part compatible with Unix (POSIX, System V, and BSD) at the source level. Compliance to Unix98-Standard is expected soon to come.
  • POSIX job control. QNX-style scheduling is possible as well.
  • Non-fragmenting filesystem "Extended 2" for filenames of 255 characters and partitions up to 4 Terabyte. Supports hard- and softlinks.
  • Support for about a dozen filesystems, among them VFAT/FAT32, Windows NT/NTFS, MacOS/HFS, QNX fs, BSD 4.3 ufs, Coda and Amiga/AFFS.
  • Up to 64 virtual consoles.
  • All source code is available, including all of the kernel and all drivers.
  • Fast. Really fast! And probably the fastest 100Mbit-Ethernet TCP/IP code on earth.
  • More pc-hardware drivers compared to any other unix; including and not limited to soundcards, ethernet-cards, ATM-cards, appletalk-devices, TV-grabbers, joysticks, ISDN-adaptors, multiport-cards etc.
  • A lot of network protocols such as TCP/IP v4 and v6, IPX/SPX, TokenRing, Ethertalk, Appletalk etc.
  • Masses of networking features, as masquerading(NAT), tunneling, forwarding, routing, firewalling and so on.

Intel 80386: Personal computers with Intel, AMD and Cyrix processors based on the X86-technology.

Intel 8086: There is a project to port Linux to the 8086. Not quite finished yet.

Power PC 604: Power Macintosh and compatibles. Note that there are two Linux-versions for the PPC: a native PPC-version and a Mach microkernel version.

Motorola 68020: Amiga or Atari ST with an 68020 need a coprocessor (or an 68030). This port works on Sun 3/80 and most Classic Macintoshs as well.

Motorola 68000: MicroLinux for 68000 processors without MMU. PalmPilot, Amiga 500, Atari ST and various embedded Systems.

MIPS R3000 Some Decstations. Maybe Nintendo 64.

ARM: Acorn Archimedes.

Alpha: DEC Alphastations and clones. This port still has performance problems.

Sparc Sun4M and above. As well as Ultrasparc Processors. This is one of the fastest and most reliable ports.


Linux needs 4 Megabytes of RAM at the very least, respectively 8 Megabytes if you're using X-Windows. 128 Megabytes are recommended. It is possible to set up a minimum system on less than 50 Megabytes of harddisk, but 1 Gigabyte is recommended. Minimum CPU on an x86 PC is an 80386SX.

Who's using it?

A lot of private persons use it for their workstations; particularly students, system administrators and programmers. Linux is also widely used among companies, which use it as server for various purposes like mail, www, fileserver, firewall or as application server. Some companies also use Linux as network manageable thin client. Linux is particularly popular among internet providers. Take a look at Swiss companies and Linux.

Why using it?

It's cheaper, faster and more scalable than a lot of the commercial systems. Overall costs are low, so the price performance ratio is great. Better hardware support compared to most other unix systems. Availability of source code. Bugs are fixed really quickly, very often within hours after detection.

Where to get help

You will get free support through numerous internet-newsgroups, mailinglists, uncounted www-pages as well as the possibility to send e-mail directly to the programmers. You may also contact your local Linux Users Group. If you need commercial support, you can turn in to one of the various distributors or to a company using and supporting Linux. Some of these might be found on the Swiss companies and linux page.


Almost everything that works on any Unix will work on Linux as well. Including Netscape Navigator/Communicator. The oncoming 86Open standard will also define a common binary format for virtually all of the X86-based unices, including SCO, Unixware, Solaris/X86, BSD and Linux of course.

The whole GNU software, including Emacs, the Gimp and the various GNU compilers, are already ported to Linux.

There are several office-type applications available on Linux, among them StarOffice, ApplixWare and KOffice.

There are several databases as well. Oracle, DB2, Informix and Sybase have already been ported to Linux.

When it comes to games, the very newest one fresh from the shop is unfortunately missing. The situation is getting better, though. iD Software will port all of their new games to Linux. A visit at Loki might be helpful as well. Their list of ported games has grown quite big.

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