Linux Is NOT UNIX - Online Article

"If you are talking about very large, massively symmetric multiprocessing systems, systems with greater than eight CPUs, you do need a full-blown Unix," says Jeremy Allison, Samba Team Lead at Fremont, Calif.-based VA Linux Systems."

There is a common misunderstanding that Linux is a refined form of UNIX or is derived form UNIX or something lie that. However, to your surprise this is NOT the case.

Linux is a Unix-like computer operating system. The name "Linux" comes from the Linux kernel started in 1991 by Linus Torvalds. Typically all underlying source code can be freely modified, used, and redistributed by anyone. It was initially a terminal emulator, which Torvalds used to access the large UNIX servers of the university.

Whereas UNIX is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. The owner of the trademark UNIX® is The Open Group, an industry standards consortium. Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX®" (others are called "Unix system-like" or "Unix-like", e.g. Linux).

Major Differences

  Linux UNIX
1 It was created by Linus Torvaldes Made by group of people at AT&T.
2 It is a kernel. It is NOT an OS It is a type of OS.
3 Linux is free. (GPL license) UNIX is not a freeware
4 Linux is just a clone of UNIX, but contains 0 UNIX kernel code.[2] -
5 Linux has small hardware requirements, relatively. Unix requires a more powerful hardware configuration.
6 It will work on both a large mainframe computer and an x86 based personal computer. It will work in large mainframe computers but will not work in an x86 based personal computer.
7 With Linux, said vendor support must be purchased, unless you buy a "boxed" set or enterprise version, and you still have to setup and configure yourself. When buying a Unix, one gets vendor assistance on setting up and configuring the system, with their people in your data centre.
8 Examples of Linux distributions are Redhat, Fedora, Susee, Mandriva, and Ubuntu. For example, BSD, Solaris uses the UNIX kernel.


  1. Linux is just the kernel the GNU (recursive acronym for GNU's Not Unix) is what people often confuse as being 'Linux' this is however the command line and tools that interact with the Linux Kernel.
  2. [From Linux Kernel ReadMe File) Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance.
  3. Interesting Facts

  4. Linux has grown faster than any other server OS over the past few years--212 percent in 1999, according to International Data Corp. (IDC). Last year Linux shipments accounted for 24.6 percent of the total server OS market, up 8.8 percent from 1998. Linux's user base is estimated to be about 15 million machines, compared to 4.5 million for combined Unix installations.
  5. A Linux OS is called a distribution and will include both the Linux Kernel and The GNU tools as well.
  6. UNIX is the foundation for a number of operating systems, with Linux being the most popular one. Novell and Free BSD are 2 other commonly used UNIX variants.
  7. Linux is programmed by a global network of people who simply code for the fun of it.
  8. UNIX was started as a project in the 60's at Berkley with AT&T and was always supposed to be open. When UNIX became a trade name that project turned into BSD which means Barkley Service Distribution.
  9. Andrew Tenenbaum was a professor and teaching Operating System and concepts but he was not able to give any examples. So, he developed his own OS called Minix. It is open but not free.
  10. Richard Stallmen (the father of open source) wanted to give a free Operating system. So, he started GNU/Hurd project. Even he itself says writing a kernel code is hard and difficult to debug so he started supporting tools like Emacs, GCC, etc.
  11. During the same time as discussed in above point, Linus Torvalds was also doing his college project. He was good enough in assembly and little C that time (before having idea of Linux). So, slowly he wrote a file system and other things.
  12. If anyone finds really something needed for Linux, the can write their own patch and then submit to Linus. Linus will then upgrade it and release in next version. However, this is not the case of BSD they don't accept patch, a major reason for their failure.

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