Michael,
Be careful. All of the options include hundreds if not thousands of distributions. I'd stick to evaluating the major ones if I were you. The three major ancestries of GNU+Linux are RedHat, Debian, and Slackware.
You shouldn't get too hung up on distros. GNU+Linux is GNU+Linux. If a program works in one distro, and you can get sources, you can usually make it work in any distro with a little time and patience. The differences you should get a feel for are how configuration is managed, how good support is on the net or on the phone, how software installation is managed, and documentation.
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Slackware is more of a hobbyiest OS, and while it works fine, its not something I'd imagine seeing in many enterprise arenas because package management is so important today, and Slackware's package management system is, well, eccentric. Slackware is published by a man named Patrick Volkerding. Slackware is Free Software, and gratis (available at no charge).
SuSE (SLED and SLES) is the largest modern embodiment of the Slackware branch today. It is published by Novell. While it is Free Software, it is not gratis (you have to pay money for it, and you get support). If you want SuSE to demo, you can get OpenSUSE, which Novell does make available gratis (free of charge). Make sure you experience it's configuration program yast. It is central to administration in SuSE.
Download Slackware at: http://www.slackware.com/getslack/ Download OpenSUSE at: http://software.opensuse.org/
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Debian is focused more on developer community and organization, than commerce, but that's not to say it won't work in a datacenter or on your desk. I work with someone who uses Debian every day, and he seems to tolerate it well. There's no single official company you'd buy Debian from and get support. Debian is Free Software and gratis (you can download it without paying).
Ubuntu is derived from Debian, and published by Canonical. Ubuntu is Free Software, and gratis. Canonical officially sells support, but I don't know anyone who buys it though. Ubuntu is more focused on user community, and "usability". I only put that in quotes, because its not like they're the only people who want the computer to be usable. Everyone does. Ubuntu just tends to put simple user experience more above other concerns than do other distributions.
Download Debian at: http://www.debian.org/distrib/ Download Ubuntu at: http://www.ubuntu.com/GetUbuntu/download
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RedHat was the first major distribution to be commercially sold. It was also avaliable at no charge originally. It was published by RedHat Inc. Today there is not a distro called RedHat. It's been split in to RHEL, and Fedora. RHEL is the "enterprisey", supported, and for-pay distro, and Fedora is the community project. RHEL intentionally excludes new software and advances so that by the time something gets included in RHEL it's not a gimmik, and it's time tested in addition to being validated by a number of vendors. RHEL does not change often. In general, when you see "Supports Linux" on a physical product, in a manual, or on a spec sheet, they're referring to RHEL. RHEL is Free Software, but is not gratis. You have to pay for it, and you get official support. RHEL is supported for extremely long. If you install RHEL on a server, the hardware will very likely become obsolete before support ends. It's not fancy. It's for the long haul.
Fedora is published by RedHat, and developed and controlled by a mix of RedHat employees, and external community. It is Free Software, and gratis. Fedora strives to include all the latest technologies and software. It also has a strong focus on only officially supporting Free Software. Things like DVDs, MP3's, and proprietary drivers are intentionally excluded from inclusion in official Fedora releases because those technologies are encumbered by restrictive patents or licenses. Fedora is released often (every 6 months), and "supported" for a relatively short period of time (eleven months from the initial release date). Fedora often retires technologies that didn't get used much or weren't as useful as originally hoped, and each release is an opportunity to make sweeping changes.
CentOS is a gratis recompile of RHEL. RedHat chooses to make their sourcecode available to download gratis even though they don't make RHEL itself available gratis. The CentOS development team literally just download the RHEL sourcecode, replace all redhat copyrighted or trademarked images and strings, and recompile. It is 100% compatible with anything that works on RHEL, and basically IS RHEL, unless you're asking for support. When you're googling for something about CentOS, you can usually substitute "rhel", and get a result in some of RedHat Inc's excellent documentation, which they make available free of charge.
Sign up for a RHEL trial at: https://www.redhat.com/apps/webform.html?event_type=simple_form&eid=871 Download Fedora at: http://fedoraproject.org/get-fedora Download Centos at: http://mirror.centos.org/centos/5/isos/
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I run Fedora Rawhide on my laptop at the moment, which is a nightly build of the very latest from Fedora. It is in effect the pre-alpha testbed of what will become the next Fedora release. I expect a few quirks, but there's not been anything I couldn't work through so far. If you come to a meeting, I'd be glad to show you how it works.
If the "Free Software not being free of charge" thing is confusing, understand the Free means Freedom, and is in no way related to monetary cost. It means people who receive the program or OS are entitled to its source code, and several rights regarding that. See http://www.gnu.org/copyleft/gpl.html
You might wish to refer to this distro timeline to get a feel for what's related to what: http://futurist.se/gldt/gldt76.png
-Billy
On Sat, Nov 1, 2008 at 03:23, Haworth, Michael A. Michael_Haworth@pas-technologies.com wrote:
At this point in the inning, Ubuntu is the first known option. As part of my job, I would be in extreme error if I didn't look at all of the options. Looks like my weekend will involve downloading SuSE and Redhat enterprise versions :)