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Unix flavors incorporate a kernel, which constitutes the core of the operating system. The kernel can access hardware and communicate with various types of user interfaces. The two most popular user interfaces are the command-line interface (called a shell) and the graphical interface (X Window). The Unix kernel is similar to the core operating system components of Windows NT and NetWare. In Unix, the kernel is typically simple and, therefore, powerful. Additionally, the kernel can be recompiled to include support for more devices. As a matter of fact, some flavors include the source code so that you can create your own flavor of Unix.


Let’s look at a few of the more popular flavors and their subtleties.


Linux


The Unix flavor that has been receiving the most attention lately is Linux. Linux is a fairly easy-to-use (as Unix goes, anyway) flavor developed by Linus Torvalds at the University of Helsinki, Finland. He started his work in 1991 and released version 1 of the Linux kernel in 1994. At the time of this writing, the current Linux kernel is version 2.2. Since Torvalds adds features daily, it’s only a matter of time before a new release.


Linux runs mainly on the Intel platform, although some distributions run on RISC processors such as the MIPS and Alpha. Attempts have been made, successfully, to run the RISC version on other platforms, such as the Macintosh. Linux is easy to install, and most distributions are free and include the source code. Hardware requirements can vary widely with each distribution.


And there are various flavors of Linux. People acquire Linux, come up with a new feature, recompile Linux with the new feature, and then redistribute Linux. According to Linux’s distribution agreement (called the GNU public license), any sale or distribution must include the source code so that others can also develop custom Linux applications.

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