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ARCHIVED: About Linux

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Introduction

Linux, originally created by Linus Torvalds, is an operating system that is freely distributed under the terms of the GNU General Public License. It behaves like Unix, but does not come from the same source code base. Linux is available in both source code and binary form.

Linux offers standard Unix-like features, such as multiuser support, multitasking, networking, and POSIX compliance. It supports all the standard Unix utilities and can compile most major Unix packages with little effort. The open source Wine compatibility layer, freely available under the terms of the GNU Lesser General Public License, enables Linux computers to run Windows applications.

The complete Linux operating system consists of the Linux core, or kernel, combined with the utilities and applications required for a fully functional operating system. Several versions, called distributions, have been developed commercially and in the open source community. Unlike Unix, which is a registered trademark of The Open Group, Linux has no official version.

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Distributions

Numerous Linux distributions are available, each containing the Linux kernel, a variety of installation and application programs, and other customized features.

Some of the earliest distributions, such as Debian, Red Hat, and Slackware, have spawned the development of multiple derivative distributions; for example:

  • Debian, an open source Linux distribution active since its initial release in 1993, was used as the basis for developing the Knoppix and Ubuntu distributions. Mint is a Linux distribution based on Ubuntu.

  • Red Hat Linux, now discontinued, was used as the basis for designing Red Hat Enterprise Linux (RHEL) and its open source counterpart, Fedora. CentOS is a Linux distribution based on RHEL.

  • Slackware, an improved version of the discontinued Softlanding Linux System (SLS), is an active open source distribution that was used as the basis for developing SUSE Linux, a commercial Linux distribution that spawned the development of openSUSE, its open source counterpart.

Each distribution has its own individual strengths and weaknesses. Some distributions are very similar to each other, with only minor differences, while others have significant differences. Also, some distributions are designed for specific types of computers.

For a graphical representation of the relationship between the various Linux distributions, see the GNU/Linux Distribution Timeline.

For more about Linux distributions, including news, reviews, and links to downloads and documentation, see the DistroWatch web site.

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Common package management programs

Many Linux distributions offer a package management system to simplify the processes associated with installing, removing, upgrading, and configuring various software packages for your computer. In a package management system, software is distributed in packages that include information dictating how the software should be installed. In addition to ensuring your software will be installed appropriately, the package manager will also determine whether you have any other software your program depends upon to run correctly. This automatic satisfying of dependencies can save you a lot of time when installing new programs.

Following are some of the most common package management programs:

  • Red Hat Package Manager (RPM): RPM is perhaps the best known package management program. For more, see In Linux, what is RPM, and how do I use it to install software?

  • Advanced Packaging Tool (APT): Initially developed for use on Debian GNU/Linux, APT has since been adapted to work with many other distributions. For more, see the APT HOWTO in the Debian User's Manual. Additionally, the manual pages for APT may be available on your system. To view them, enter: man apt
  • Portage: Designed for Gentoo Linux, Portage offers functionality similar to that of the package management systems discussed above. Additionally, Portage is the primary distribution system for Gentoo Linux software. For more, see the Gentoo Documentation Resources page.

    The emerge command provides a command line interface to Portage. To view the manual pages for emerge, enter:

    man emerge

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Availability

On CD-ROM

You can find Linux CD-ROMs with printed manuals in many bookstores (including online bookstores).

Some of the boxed distributions commercial vendors produce come with additional email or phone support services available only to customers who purchase their official CD-ROM packages.

For a low price, you can also purchase CD-ROMs without any printed manuals or support. For more, see the Linux Central web sites.

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On the Internet

Many distributors offer free Linux downloads via their web sites. Alternatively, you can many Linux distributions available for download from the ibiblio Linux archive. Each separate subdirectory at this location contains the files of a different Linux distribution. In some cases, older releases of the distribution are available, as well as extra software such as "power tools".

Note: Some of the older, less prominent distributions available from the ibiblio Linux archive are outdated with regard to the latest kernel releases or known security problems.

If you want only the Linux kernel itself, not an entire distribution, see the Linux Kernel Archives home page.

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At IU

Note: Indiana University has a site license covering the use of Red Hat Enterprise Linux (RHEL) by students, faculty, and staff at IU. For details, see IU's software agreement with Red Hat.

IU students, faculty, and staff can download RHEL at no cost via IUware. UITS mirrors other Linux distributions, the entire Linux Documentation Project, and scripts and configuration advice relevant to the IU community at:

ftp://ftp.ussg.iu.edu/pub/linux/

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Online documentation

An extensive body of Linux documentation is available online via the Linux Documentation Project, which provides guides, FAQs, security information, manual pages, links to software development projects and software distributors, and online copies of numerous Linux manuals.

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Support at IU

At Indiana University, for personal or departmental Linux or Unix systems support, see Linux and Unix support at IU

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