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Tuesday, September 12, 2006

RedHat Linux


Red Hat Enterprise Linux (often abbreviated to RHEL) is a Linux distribution produced by Red Hat and targeted toward the commercial market, including mainframes. Red Hat commits to supporting each version of RHEL for 7 years after its release. All of Red Hat's official support, and all of Red Hat's training and certification for hardware and software deployment — Red Hat Certified Technician (RHCT), Red Hat Certified Engineer (RHCE), Red Hat Certified Security Specialist (RHCSS) and Red Hat Certified Architect (RHCA) — center on the Red Hat Enterprise Linux platform.
New versions of RHEL are released every 18 to 24 months. When Red Hat releases a new version of RHEL, customers may upgrade to the new version at no additional charge as long as they are in possession of a current subscription (e.g. the subscription term has not yet lapsed).
Red Hat's first Enterprise offering (Red Hat Linux 6.2E) essentially consisted of a version of Red Hat Linux 6.2 with different support levels, and without separate engineering.
The first version of RHEL to bear the name originally came onto the market as "Red Hat Linux Advanced Server". In 2003 Red Hat rebranded Red Hat Linux Advanced Server to "Red Hat Enterprise Linux" (RHEL) AS, and added two more variants, RHEL ES and RHEL WS.


Variants
As of 2005 Red Hat distributed four variants of RHEL:
RHEL AS (advanced
server) – for larger computer systems
RHEL ES (edge server or entry-level server) – for medium systems
RHEL WS (workstation) – for personal
power-user desktops
Red Hat Desktop – for
client-oriented single-user use
There are also "Academic" editions of the Desktop and Server variants. They are offered to schools and students, are less expensive, and are provided with Red Hat technical support as an optional extra. Web support based on number of customer contacts can be purchased separately.
People sometimes mistakenly refer to ES as "
Enterprise Server", in contrast to AS (Advanced Server). This may be because Novell has a server distribution called SUSE Linux Enterprise Server (SLES). Also, nowhere on its site or in its literature does Red Hat say what the abbreviations AS, ES and WS stand for.

Debian Linux


Debian, organized by the Debian Project, is a widely used distribution of free software developed through the collaboration of volunteers from around the world. Since its inception, the released system, Debian GNU/Linux, has been based on the Linux kernel, with many basic tools of the operating system from the GNU project.
Debian is known for its adherence to the Unix and free software philosophies, and for its abundance of options—the current release includes over fifteen thousand software packages for eleven computer architectures, ranging from the ARM architecture commonly found in embedded systems and the IBM s390 mainframe architecture to the more common x86 and PowerPC architectures found in modern personal computers. Debian GNU/Linux is the basis for several other distributions, including Knoppix and Ubuntu.
Debian is also known for its package management system, especially APT, for its strict policies regarding the quality of its packages and releases, and for its open development and testing process. These practices afford easy upgrades between releases without rebooting and easy automated installation and removal of packages.
Debian is supported by donations through Software in the Public Interest, Inc., a non-profit umbrella organization for free software projects.

SUSE Linux

History

The SUSE Linux distribution was originally a German translation of
Slackware Linux. In mid-1992, Softlanding Linux System (SLS) was founded by Peter MacDonald, and was the first comprehensive distribution to contain elements such as X and TCP/IP. The Slackware distribution (maintained by Patrick Volkerding) was initially based largely on SLS.
S.u.S.E was founded in late 1992 as a
UNIX consulting group, which among other things regularly released software packages that included SLS and Slackware, and printed UNIX/Linux manuals. S.u.S.E is an acronym for the German phrase "Software- und System-Entwicklung" ("Software and system development"). There is an unofficial rumour that the name is a tribute to the German computer pioneer Konrad Zuse. They released the first CD version of SLS/Slackware in 1994, under the name S.u.S.E Linux 1.0. It later integrated with the Jurix distribution of Florian La Roche, to release the first really unique S.u.S.E Linux 4.2 in 1996. Over time, SuSE Linux incorporated many aspects of Red Hat Linux (e.g., using RPMs and /etc/sysconfig).
The name "S.u.S.E." shortened to just "SuSE" in October
1998.
On
November 4, 2003, Novell announced it would acquire SuSE (Shankland, 2003). The acquisition was finalized in January 2004 (Kennedy, 2003) and the company's name was changed to SUSE Linux after Novell's purchase. "SuSE" does not officially stand for anything anymore. According to Ramesh (2004), J. Philips (Novell's corporate technology strategist for the Asia Pacific region) stated that Novell would not "in the medium term" alter the way in which SUSE continues to be developed. At Novell's annual BrainShare gathering in 2004, all computers ran SUSE Linux for the first time. At this gathering it was also announced that the proprietary SUSE administration program YaST2 would be released into the public under the GPL license.
On
August 4, 2005, Novell spokesman and director of public relations Bruce Lowry announced that the development of the SUSE Professional series will become more open and within the community project openSUSE try to reach a wider audience of users and developers. The software, by definition of open source, already had their coding "open," but now the development process will be more "open" than before, allowing developers and users to test the product and help develop it. Previously all development work was done in-house by SUSE, and version 10.0 was the first version that had public beta testing. As part of the change, YaST Online Update server access will be complimentary for SUSE Linux users, and along the lines of most open source distributions, there will both be a free download available on the web and a boxed edition. This change in philosophy led to the release of the SUSE Linux 10.0 release on October 6, 2005 in "OSS" (completely open source), "eval" (has both open source and proprietary applications and is actually a fully-featured version) and retail boxed-set editions.

Features

SUSE includes an installation and administration program called
YaST2 which handles hard disk partitioning, system setup, RPM package management, online updates, network and firewall configuration, user administration and more in an integrated interface.
Starting with the 10.1 release, SuSE includes a secondary installation program known as Zen-Updater, which can be used as a secondary means of installing software and replaces Suse-updater providing notification of software updates on the desktop.
SUSE has support for resizing
NTFS partitions during installation which allows it to co-exist with existing Windows 2000 or XP installations. SUSE has the ability to detect and install drivers for many common winmodems shipped with OEM desktop and laptop systems (such modems are designed to use Windows-specific software to operate).
Several
desktop environments such as KDE and GNOME and window managers like Window Maker and Blackbox are included, with the YaST2 installer allowing the user to choose a preselection of GNOME, KDE, or no desktop at all. SUSE ships with multimedia software such as K3B (CD/DVD burning), Amarok (audio playback), and Kaffeine (movie playback). It contains OpenOffice.org, and software for reading and/or creating other common document formats such as PDF. Due to patent problems, the distribution lacks codecs for proprietary formats like mp3 or avi, but these can be installed with packages available on the internet.

Versions


The latest release, SUSE Linux 10.1 is available as a retail package and a free, open source package, referred to as SUSE Linux OSS. In terms of software, the two are nearly identical. The major difference between the two is the retail edition contains some proprietary components, such as Macromedia Flash. In addition, the retail package, available for 59.95 USD, includes a printed manual and limited technical support. SUSE Linux OSS is available to download freely from their website. The retail and eval versions contain one DVD and six CDs, while SUSE Linux OSS uses five CDs.
Other flavours include dedicated server editions and groupware servers geared towards corporate networks and enterprises, along with a stripped-down business desktop which runs some software designed for
Microsoft Windows out of the box by virtue of WINE.
SUSE Linux Enterprise Server (SLES) and SUSE Linux Enterprise Desktop (SLED) are Novell's branded version of SUSE targeted at corporate environments. SUSE Linux Enterprise product line (SLES and SLED) include some proprietary software as well as technical support. For instance, SuSE Linux Enterprise Server 9 (SLES 9) has fewer packages (around 1,000 packages) than the SuSE Linux Professional (consumer) distribution which has around 3,500 packages. Most of the packages that have been removed are desktop applications which are more suited to consumers than to a business environment. SLES has a guaranteed life cycle of 5 years and only the SLES products are certified by independent hardware and software vendors.

Distribution

In the past SUSE first released the Personal and Professional versions in boxed sets which included extensive printed documentation, then waited a few months before it released versions on its
FTP servers. Under Novell and with advent of openSUSE this has been reversed: SUSE Linux 10.0 was available for download well before the retail release of SUSE Linux 10.0. In addition, Novell has discontinued the Personal version, renamed the Professional version to simply "SUSE Linux", and repriced "SUSE Linux" to about the same as the obsolete Personal version. Now Novell has also announced that SUSE Linux will be renamed to openSUSE starting from version 10.2 of the distro.
Starting with version 9.2, an unsupported 1 DVD
ISO image of SUSE Professional was made available for download as well as a bootable LiveDVD evaluation. The FTP server continues to operate and has the advantage of "streamlined" installs: Only downloading packages the user feels they need. The ISO has the advantages of an easy install package, the ability to operate even if the user's network card does not work 'out of the box', and less experience needed (i.e., a Linux newbie may not know whether or not to install a certain package, and the ISO offers several preselected sets of packages). The retail box DVD supports x86, and x86_64 installs, but the included CD-ROMs do not include x86_64 support.

Linux Distributions

Linux is predominantly used as part of a Linux distribution (commonly called a "distro"). These are compiled by individuals, loose-knit teams, and commercial and volunteer organizations. They commonly include additional system and application software, an installer system to ease initial system setup, and integrated management of software installation and upgrading. Distributions are created for many different purposes, including computer architecture support, localization to a specific region or language, real-time applications, and embedded systems, and many deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.
A typical general-purpose distribution includes the Linux kernel, some GNU libraries and tools, command-line shells, the graphical X Window System and an accompanying desktop environment such as KDE or GNOME, together with thousands of application software packages, from office suites to compilers, text editors, and scientific tools.

Linux Installation


The most common method of installing Linux on a personal computer is by booting from a CD-ROM that contains the installation program and installable software. Such a CD can be burned from a downloaded ISO image, purchased alone for a low price, can be obtained as part of a box set that may also include manuals and additional commercial software and in a few cases shipped for free by request. Mini CD images allow Linux to be installed from a disk with a small form factor.
As with servers, personal computers that come with Linux already installed are available from vendors including Hewlett-Packard and Dell, although generally only for their business desktop line.
Alternatives to traditional desktop installation include thin client installation, where the operating system is loaded and run from a centralised machine over a network connection; and running from a Live CD, where the computer boots the entire operating system from CD without first installing it on the computer's hard disk.
On embedded devices, Linux is typically held in the device's firmware and may or may not be consumer-accessible.

Development efforts


More Than a Gigabuck: Estimating GNU/Linux's Size, a 2001 study of Red Hat Linux 7.1, found that this distribution contained 30 million source lines of code. Using the Constructive Cost Model, the study estimated that this distribution required about eight thousand man-years of development time. According to the study, if all this software had been developed by conventional proprietary means, it would have cost about 1.08 billion dollars (year 2000 U.S. dollars) to develop in the United States.
The majority of the code (71%) was written in the C programming language, but many other languages were used, including C++, Lisp, assembly language, Perl, Fortran, Python and various shell scripting languages. Slightly over half of all lines of code were licensed under the GPL. The Linux kernel was 2.4 million lines of code, or 8% of the total.
In a later study, Counting potatoes: The size of Debian 2.2, the same analysis was performed for Debian GNU/Linux version 2.2. This distribution contained over fifty-five million source lines of code, and the study estimated that it would have cost 1.9 billion dollars (year 2000 U.S. dollars) to develop by conventional means.

Linux and the GNU Project


The goal of the GNU project is to produce a Unix-compatible operating system consisting entirely of free software, and most general-purpose Linux distributions rely on GNU libraries and tools written to that effect. The Free Software Foundation views these Linux distributions as "variants" of the GNU system, and asks that such operating systems be referred to as GNU/Linux or a Linux-based GNU system.
While some distributions make a point of using the combined form - notably Debian GNU/Linux - its use outside of the enthusiast community is limited, and Linus Torvalds has said that he finds calling Linux in general GNU/Linux "just ridiculous" [11]. The distinction between the Linux kernel and distributions based on it is a source of confusion to many newcomers, and the naming remains controversial.

Linus Torvalds - 25 August 1991 - posts to comp.os.minix


"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since April, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things).
I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that I'll get something practical within a few months [...] Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT portable (uses 386 task switching etc), and it probably never will support anything other than AT-harddisks, as that's all I have :-(.
[...] It's mostly in C, but most people wouldn't call what I write C. It uses every conceivable feature of the 386 I could find, as it was also a project to teach me about the 386. As already mentioned, it uses a MMU, for both paging (not to disk yet) and segmentation. It's the segmentation that makes it REALLY 386 dependent (every task has a 64Mb segment for code & data - max 64 tasks in 4Gb. Anybody who needs more than 64Mb/task - tough cookies). [...] Some of my "C"-files (specifically mm.c) are almost as much assembler as C. [...] Unlike minix, I also happen to LIKE interrupts, so interrupts are handled without trying to hide the reason behind them "

what is linux history ?



In 1983, Richard Stallman founded the GNU Project, with the goal of developing a complete Unix-like operating system composed entirely of free software. By the beginning of the 1990s, GNU had produced or collected most of the necessary components of this system—libraries, compilers, text editors, a Unix-like shell—except for the core component, the kernel. The GNU project began developing a kernel, the Hurd, in 1990, based on the Mach microkernel, but the development of this Mach-based design proved difficult and proceeded slowly.
Meanwhile, in 1991, another kernel was begun as a hobby by Finnish university student Linus Torvalds while attending the University of Helsinki. Torvalds originally used Minix on his own computer, a simplified Unix-like system written by Andrew Tanenbaum for teaching operating system design. However, Tanenbaum did not permit others to extend his operating system, leading Torvalds to create a replacement for Minix.
Originally, Torvalds called his kernel "Freax" for "free" and "freak" and with the often-used X in the names of Unix-like systems. The name "Linux" was coined by Ari Lemmke, who administered an FTP server belonging to the Finnish University Network; he invented the name Linux for the directory from which Torvalds' project was first available for download.

A graphic history of Unix systems. Linux is a Unix-type system but its source code does not descend from the original Unix.
At first a computer running Minix was necessary in order to configure and install Linux. Initial versions of Linux also required another operating system to be present in order to boot from a hard disk, but soon there were independent boot loaders such as LILO. The Linux system quickly surpassed Minix in functionality; Torvalds and other early Linux kernel developers adapted their work for the GNU components and user-space programs to create a complete, fully functional, and free operating system.
Today, Torvalds continues to direct the development of the kernel, while other subsystems such as the GNU components continue to be developed separately (Linux kernel development is not part of the GNU Project). Other groups and companies combine and distribute these components with additional application software in the form of Linux distributions.

Whats is Linux ?


Linux (also known as GNU/Linux) is a Unix-like computer operating system. It is one of the most prominent examples of open source development and free software; unlike proprietary operating systems such as Windows or Mac OS X, all of its underlying source code is available for anyone to use, modify, and redistribute freely.

Initially, Linux was primarily developed and used by individual enthusiasts on personal computers. Since then, Linux has gained the support of major corporations such as IBM, Sun Microsystems, Hewlett-Packard, and Novell for use in servers and is gaining popularity in the desktop market.
It is used in systems ranging from supercomputers to mobile phones. Proponents and analysts attribute its success to its security, reliability, low cost, and freedom from vendor lock-in
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Monday, September 11, 2006

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Hello every body ....

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