What Is Linux?

What is operating system?

The operating system is software that manages all the hardware and runs other software at your command. You, the user, provide those commands by clicking menus and icons or by typing some cryptic text. Linux is an operating system — as are UNIX, Windows 98, Windows 2000, and Windows XP.

What Is Linux?

The Linux operating system is modeled after UNIX; in its most basic, no-frills form, the Linux operating system also goes by the name Linux kernel.The operating system is what gives a computer — any computer — its personality.For example, you can run Windows 98 or Windows XP on a PC —and on that same PC, you can also install and run Linux. That means that depending on which operating system is installed and running at any particular time, the same PC can be a Windows 98, Windows XP, or Linux system.

In technical words, Linux is a multiuser, multitasking operating system. All this means is that Linux enables multiple users to log in, and Linux can run more than one program at the same time. Nearly all operating systems are multiuser and multitasking these days, but when Linux first
started in 1994, multiuser and multitasking were big selling points.

Linux distributions

A Linux distribution consists of the Linux kernel (the operating system) and a collection of applications, together with an easy-to-use installation program.By the way, most people just say Linux to refer to a specific Linux distribution

 Below is a few major Linux distributions lists

 Ubuntu

 Ubuntu has stormed the Linux distribution scene like no other Linux project before. It has done so in a fashion resembling a highly sophisticated player: it seems to have first observed all other major distributions, learnt from their mistakes and combined the best features of all of them into one superior product. A six-month's release cycle, up-to-date package set, a clearly set product lifetime (at 18 months), fast download mirrors, great documentation, even free CDs and free shipment of CDs anywhere in the world to those interested in the distribution. That's Ubuntu.

The project is funded by Mark Shuttleworth. Those who have never heard the name, Mark is a South African entrepreneur who made a fortune when he sold his company, Thawte Consulting, to Verisign, for US$575 million in late 1999. He appears to be a generous person: after the sale, he reportedly paid bonuses of one million Rand each (about US$163,000 at the time) to every one of his employees. He also founded several educational and open source initiatives around South Africa, including Go Open Source. While it is not yet clear how Mark's Canonical Limited intends to make money from Ubuntu, the distribution is certainly off to a good start, at least in terms of getting the name into public consciousness and offering a solid alternative to more established Linux distributions.

On the technical side of things, Ubuntu is based on Debian Sid (unstable branch), but with more up-to-date packages, inclusive of the latest GNOME packages. The distribution is designed to be used on desktops and servers, with a supported upgrade path from Debian 3.0 (Woody). One of its more interesting features is the fact that the "root" account is disabled by default; the first registered user after installation is granted superuser privileges through the "sudo" command. This measure, while it might sound like an inconvenience at first, has to be applauded since it encourages good security practices.

Pros: Great community of developers and users; fixed release cycle and support period; upgrade path from stable Debian provided
Cons: Ubuntu's backers have not yet built a viable business model around the distribution
Software package management: APT (DEB)
Free download: Yes

Mandriva Linux

Mandriva Linux (formerly Mandrakelinux), started by Gaël Duval, is a distribution that has experienced enormous rise in popularity since its first release in July 1998. The developers took the Red Hat distribution, changed the default desktop to KDE and added an easy-to-use installer, breaking the myth that Linux is hard to install. Mandrake's hardware detection features and disk partitioning utilities are considered by many to be the best in the industry and many users found themselves running Mandrake where other distributions failed to provide the required usability.

Mandriva Linux has since matured to become a popular distribution among those new to Linux and among home users looking for an alternative operating system. The Mandriva development is completely open and transparent with new packages appearing in the so-called "cooker" directory on a daily basis. When a new release is entering a beta stage, a cooker snapshot is accepted as the first beta. The beta testing process used to be short and intensive, but starting with version 9.0, it has become longer and more thorough. The beta mailing lists are extremely busy, but you are still likely to receive a very fast response to any bug or concern that you report.

The result of this type of development is a cutting edge release - a highly up-to-date Linux distribution. As a trade-off, the users are likely to notice more bugs and perhaps less stability than with other distributions. Many people find this trade-off acceptable on their desktops - they get the very latest software and the occasional application crash is something they can live with.

Pros: User-friendly, graphical configuration utilities, enormous community support, NTFS partition resizing.
Cons: Some releases are buggy, the releases are initially made available to MandrivaClub members only.
Software package management: urpmi (RPM)
Free download: FTP installation available immediately after release, ISO images only after a delay lasting several weeks

SUSE

SUSE (formerly SuSE or "Software und System Entwicklung") was established by a group of German developers in 1992. In the early days, the company sold sets of floppy disks containing a German edition of Slackware Linux, but it wasn't long before SUSE became an independent Linux distribution with the launch of version 4.2 in May 1996. In the following years, SUSE adopted the RPM package management format and developed YaST, an easy-to-use graphical system administration tool. Frequent releases, excellent documentation, and easy availability of SUSE Linux in stores across Europe and North America resulted in growing popularity of SUSE Linux.

SUSE was acquired by Novell in late 2003. Major changes in the development and availability of SUSE Linux followed shortly afterwards - YaST was released under the General Public License, the ISO images were freely distributed from dozens of public download servers, and, most significantly, the development of SUSE Linux was opened to public participation for the first time ever. Since the launch of the openSUSE project and the release of version 10.0 in October 2005, SUSE Linux has become a completely free distribution in both senses of the word.

Starting from version 10.0, SUSE Linux comes in several editions: the 5-CD "OSS" (Open Source Software) edition contains exclusively Free Software, while the 5-CD (or 1-DVD) "Eval" edition adds some proprietary, but freely-distributable packages. The retail edition of SUSE Linux includes extra commercial software, documentation, and installation support. A bootable "Live DVD" edition is provided for those who wish to test-drive SUSE Linux without the need to install it on their computers.

Pros: Professional attention to detail, easy-to-use YaST configuration tools.
Cons:
Software package management: YaST (RPM), third-party APT (RPM) repositories available
Free download: Yes

Red Hat

 For many, the name Red Hat epitomises Linux, as it is probably the best-known Linux company in the world. Founded in 1995 by Bob Young and Marc Ewing, Red Hat, Inc. has only recently started showing signs of profitability, due to services and its Red Hat Enterprise Linux product line. However, Red Hat Linux 9 was the last version in the Red Hat Linux product line, which was replaced by Fedora Core in late 2003. While Fedora is officially sponsored by Red Hat, it is developed with community participation, has a short life-span and serves mainly as a testing base for Red Hat Enterprise Linux.

What is so special about Red Hat Linux and Fedora Core? It is a curious mix of conservative and leading-edge packages put together on top of many knowledge-intensive utilities developed in-house. The packages are not the most up-to-date; once a new beta version is announced, the package versions are frozen, except for security updates. The result is a well-tested and stable distribution, the beta program and bug reporting facility are open to the public and there are several mailing lists. Red Hat Linux has become a dominant Linux distribution on servers around the world.

One other reason for Red Hat's success is the variety of popular services the company offers. The software packages are easy to update via Red Hat Network, a free repository of software and valuable information. A vast range of support services and enterprise Linux products are available from the company and, while not always cheap, you are virtually assured of an excellent support by highly skilled support personnel. The company has even developed a certification program to further popularise its distribution - the RHCE (Red Hat Certified Engineer) training and examinations are now available in most parts of the world. All these factors have contributed to the fact that Red Hat is now a recognised brand name in the IT industry.

Pros: Widely used, excellent community support, lots of innovation.
Cons: Limited product life-span of the free edition, poor multimedia support, concerns over the Red Hat to Fedora transition
Software package management: up2date (RPM), YUM (RPM)
Free download: Yes

Debian GNU/Linux

Debian GNU/Linux, started by Ian Murdock in 1993, is a completely non-commercial project; perhaps the purest form of the ideals that started the free software movement. Hundreds of volunteer developers from all over the world contribute to the project, which is well managed and strict, assuring a quality distribution known as Debian.

At any time during the development process, there are three branches in the main directory tree - "stable", "testing" and "unstable" (also known as "sid"). When a new version of a package appears, it is placed in the unstable branch for early testing. If it passes, the package moves to the testing branch, which undergoes rigorous testing lasting many months. This branch is only declared stable after a very thorough testing. As a result of this, the distribution is possibly the most stable and reliable, albeit not the most up-to-date. While the stable branch is perfect for use on mission critical servers, many users prefer to run the more up-to-date testing or unstable branches on their personal computers.

One of the most pleasant aspect of Debian is its "apt-get" utility, a convenient front-end for the "dpkg" software installation and management tool. Although packages managers of other distributions have caught up with Debian in terms of convenience, dpkg and apt-get, together with the traditionally high standards of Debian packaging and quality control, remain the most advance package management utilities available today.

Pros: 100% free, excellent documentation and community resources, well-tested, painless software installation with apt-get.
Cons: Slow release cycle, the stable version tends to be out-dated.
Software package management: APT (DEB)
Free download: Yes