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Learning linux severs: Red Hat or Centos ?

Hi there, I have a question, please. I'm new to linux and I'm learning with unix academy training DVDs. The training comes bundled with many Linux distros, and I initially installed and been using Ubuntu for my lessons (it was a random choice). I do have IT experience, but not with Linux (databases, app servers, win admin). I know that Red Hat is most widely used, when it comes to large scale enterprise installations.

Now I'm stuck in a confusion: is CentOS really the same as Red Hat, and could it be used for training for Red Hat? Are these two absolutely identical?

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Comments

  • atreyuatreyu Posts: 216
    The short answer is "yes". My understanding of CentOS is, they ripped out everything proprietary from Red Hat (logos, etc.) and rebuilt the packages from the source RPMS (that Red Hat is obliged to provide).

    I can tell you that I support Red Hat EL servers at my work and we use CentOS all the time for our development servers and workstations, when we can get away with it (i.e. when customer does not require RHEL) b/c we have never once run into an issue using it instead of RHEL. For example, every piece of code that we write (and package as an RPM) we can install onto a CentOS box and it works perfectly. Similarly, we can take any package that was built for a RHEL system (either binary or rebuilt from SRPM, if we feel like doing the extra work - but usually is not necessary) and install it on CentOS again, with no compatibility problems whatsoever.

    Plus, it is a great way to have a RHEL server at home for you to play with, and not have to worry about the license.

    -bill
  • anand44anand44 Posts: 11
    atreyu wrote:
    The short answer is "yes". My understanding of CentOS is, they ripped out everything proprietary from Red Hat (logos, etc.) and rebuilt the packages from the source RPMS (that Red Hat is obliged to provide).

    I can tell you that I support Red Hat EL servers at my work and we use CentOS all the time for our development servers and workstations, when we can get away with it (i.e. when customer does not require RHEL) b/c we have never once run into an issue using it instead of RHEL. For example, every piece of code that we write (and package as an RPM) we can install onto a CentOS box and it works perfectly. Similarly, we can take any package that was built for a RHEL system (either binary or rebuilt from SRPM, if we feel like doing the extra work - but usually is not necessary) and install it on CentOS again, with no compatibility problems whatsoever.

    Plus, it is a great way to have a RHEL server at home for you to play with, and not have to worry about the license.

    -bill


    +1 CentOS is definitely is a free version of Red Hat Fedora.
  • marcmarc Posts: 647
    brunewarren wrote:
    Hi there, I have a question, please. I'm new to linux and I'm learning with unix academy training DVDs. The training comes bundled with many Linux distros, and I initially installed and been using Ubuntu for my lessons (it was a random choice). I do have IT experience, but not with Linux (databases, app servers, win admin). I know that Red Hat is most widely used, when it comes to large scale enterprise installations.
    Now I'm stuck in a confusion: is CentOS really the same as Red Hat, and could it be used for training for Red Hat? Are these two absolutely identical?

    They are not identical but are 100% binary compatible.

    Centos rebuilds the sources packages from Red Hat free from any copyrighted material and that's it :)

    You can perfectly use CentOs to learn RedHat systems management (although some commands may change names)

    I would also suggest giving a try to Scientific Linux :)

    Regards
  • All right, so for all my training purposes I can use CentOS.
  • marcmarc Posts: 647
    brunewarren wrote:
    All right, so for all my training purposes I can use CentOS.

    Nice chosing :)

    My server runs centos as well as the work servers. It's a very good server OS and amazing for learning purposes as you can use Red Hat's documentation (docs.redhat.com)

    Regards
  • woboylewoboyle Posts: 501
    CentOS is 100% binary compatible with RHEL, but currently the most up-to-date version is 5.6. If you want support for newer hardware (wireless, bluetooth, web-cams, and such) then try Scientific Linux 6. It is also a RHEL clone, but at version 6 (latest and "greatest"). I am using it now, and am quite happy with it. Hardware that didn't work with CentOS 5.x does work now.
  • saqman2060saqman2060 Posts: 777
    As far as I know, CentOS is the same of RedHat. It is just the free version of it.
  • marcmarc Posts: 647
    saqman2060 wrote:
    As far as I know, CentOS is the same of RedHat. It is just the free version of it.

    No no no no no no no and NO

    I've already explain what CentOS is. It's free; it's based on RedHat's source. It is *not* the "free version" of RedHat.

    There's a difference, ya know ;)
  • In functionality terms it can be considered the systems clones.
    The difference this in the support.
    The support of the Centos is not paid.
    The support of the Redhat is paid.
  • Goineasy9Goineasy9 Posts: 1,116
    Your both correct. The RedHat guys on the fedora-devel mailing list consider CentOS to be RedHat without the trademarks. BUT, it is not put out by RedHat, so, it can't claim to be the free version of RedHat, although, it is in all respects it is a free version of RedHat. CentOS still hasn't come out with version 6 yet, so, if one wants to experience RedHat 6, the alternative is to use Scientific Linux, which is based on RedHat 6 but is certainly not a clone of RedHat 6. Now, is everyone confused? Or should I continue?
  • The reason has all after all the Centos is derived from codes source freely distributed by Red Hat Enterprise Linux.
  • brunewarrenbrunewarren Posts: 14
    Ok, guys thanks!
  • brunewarrenbrunewarren Posts: 14
    Guys when you say "binary compatible" does it mean that all the commands have the same options and behave in a same way? I have been learning command line commands with UNIX Academy training DVDs and I see they have many options. My concern is, are these options are the same across Linux flavors or there are variations?
  • atreyuatreyu Posts: 216
    brunewarren wrote:
    Guys when you say "binary compatible" does it mean that all the commands have the same options and behave in a same way? I have been learning command line commands with UNIX Academy training DVDs and I see they have many options. My concern is, are these options are the same across Linux flavors or there are variations?
    Yes, that is what binary compatible means. In other words, the "ls" program from the "coreutils" package in CentOS 5.5 has the exact same options and works the same way as the "ls" program from the "coreutils" package in RHEL 5.5.

    However, that does not mean that some utility would behave the same way in some other Linux flavor that is not binary compatible. A utility may be patched by the distro packager to behave more efficiently w/in that OS or may merely be an updated version of that package. For example, the "nmap" utility on Ubuntu 9.04 is nmap version 4.76 and is definitely not going to have all the same options and work the same way as "nmap" in Fedora 12, which is nmap version 5.00-3. The version of nmap on Fedora 11 is nmap version 4.76, but even then, it would not be binary compatible with the nmap in Ubuntu 9.04 because it was built against a slightly different version of libraries and probably has different patches applied to it, even though the nmap command may have the same options and work for all intents and purposes, the same way on both distros.
  • marcmarc Posts: 647
    atreyu wrote:
    Yes, that is what binary compatible means. In other words, the "ls" program from the "coreutils" package in CentOS 5.5 has the exact same options and works the same way as the "ls" program from the "coreutils" package in RHEL 5.5.

    Be carefull with that. Same options is a consecuence of being "binary compatible". In fact, you could have *exactly* the same command line options and *NOT* be binary compatible-> you have here the born of Linux! A Unix clone!

    Example of binary compatible: you can take a "program" from a RedHat installation, place it in a CentOS system and run it without any hassle. That's because they're linked against libraries with exact same compilation options, same kernel... those sort of things.

    That's different from having the same options! The programs don't even need to have the same name (check the Directory Server on both CentOS and RedHat... they have different names but are binary compatible ;) ).


    Now, for the questions about diferences from one vendor/distribution to another: *there are*. Not many though.

    If you learn RedHat's command line options you'll be fine in most of the *nix systems (yes, not only linux).

    Regards
  • woboylewoboyle Posts: 501
    There are two major clones of Red Hat Enterprise Linux - CentOS (Community Enterprise Operating System), and SL (Scientific Linux). I used CentOS 5.x for 3 years and switched to SL at the beginning of the year as CentOS was delaying release of version 6. They are both good distributions, but SL, to my mind, has the advantage of serious government and university support - it runs the servers for most major scientific labs in the world, including Fermi National Laboratory and Argonne National Laboratory in Illinois, and CERN in Switzerland.
  • marcmarc Posts: 647
    woboyle wrote:
    There are two major clones of Red Hat Enterprise Linux - CentOS (Community Enterprise Operating System), and SL (Scientific Linux). I used CentOS 5.x for 3 years and switched to SL at the beginning of the year as CentOS was delaying release of version 6. They are both good distributions, but SL, to my mind, has the advantage of serious government and university support - it runs the servers for most major scientific labs in the world, including Fermi National Laboratory and Argonne National Laboratory in Illinois, and CERN in Switzerland.

    The university support is something that is pushing me to use SL on my servers... if only my cloud provider would give it as an option...

    I can't test it on my home server as my cpu has no PAE support :(

    Regards
  • brunewarrenbrunewarren Posts: 14
    Interesting, I have never heard of SL before...
  • Goineasy9Goineasy9 Posts: 1,116
    It was interesting that Scientific Linux was the first to come out with a Red Hat 6 clone, while Centos, which always followed Red Hat releases by a couple of weeks, has still been unable to release one. From some DistroWatch comments it seems there is trouble in Centos Land.
    With so many businesses using Centos, I hope this is not the case. But, from different mailing lists, I'm seeing a migration to Scientific.
  • atreyuatreyu Posts: 216
    You bring up a good point, Goineasy9. I depend on CentOS a lot and right now, we're happy on 5.x, but if we need to support a RH 6 soon, SL may be the way to go.

    This is a good read on the subject (from Brian Proffitt, posted yesterday):
    http://www.itworld.com/open-source/166067/hyper-v-shines-spotlight-centos-ready-soon-60-release
  • marcmarc Posts: 647
    atreyu wrote:
    You bring up a good point, Goineasy9. I depend on CentOS a lot and right now, we're happy on 5.x, but if we need to support a RH 6 soon, SL may be the way to go.

    This is a good read on the subject (from Brian Proffitt, posted yesterday):
    http://www.itworld.com/open-source/166067/hyper-v-shines-spotlight-centos-ready-soon-60-release

    Well, some clarifications:

    1st: SL hasn't released a 5.6 version whereas CentOS has.

    2nd (and importand one): CentOS support is *longer*

    The thing is that one of the main centos developers (Dag) left the project months ago and they've been restructuring

    Regards
  • atreyuatreyu Posts: 216
    marc wrote:
    1st: SL hasn't released a 5.6 version whereas CentOS has.

    2nd (and importand one): CentOS support is *longer*

    The thing is that one of the main centos developers (Dag) left the project months ago and they've been restructuring

    Regards
    Fortunately, we are solidly entrenched in 5.5 so we're not affected by that.
    That definitely hurts losing Dag. I've been benefiting from his hard work for years. I remember reading about his laptop getting stolen and him losing a lot of work.
  • brunewarrenbrunewarren Posts: 14
    So what loosing one (even key) developer puts the entire Centos project to restructuring?
  • marcmarc Posts: 647
    brunewarren wrote:
    So what loosing one (even key) developer puts the entire Centos project to restructuring?

    Not at all, CentOS is well and alive.

    Besides, the 6.0 version is due to be out in a couple of days...

    Regards
  • Goineasy9Goineasy9 Posts: 1,116
    marc wrote:
    brunewarren wrote:
    So what loosing one (even key) developer puts the entire Centos project to restructuring?

    Not at all, CentOS is well and alive.

    Besides, the 6.0 version is due to be out in a couple of days...

    Regards

    That's good news, I just read the Distrowatch comment about it. Although I do think that Scientific Linux is still an interesting alternative, especially since I learned what it was designed for.
    Centos also claims the the 6.1 release will follow after a few weeks after the 6.0 release. I'm glad they sorted things out.
  • brunewarrenbrunewarren Posts: 14
    May be I'm wrong, but to my eye, eventually most of these branched out Linux clones will go away. There are too many.
  • marcmarc Posts: 647
    brunewarren wrote:
    May be I'm wrong, but to my eye, eventually most of these branched out Linux clones will go away. There are too many.

    Well, that depends...

    CentOS has been out there for many years...

    Regards
  • Goineasy9Goineasy9 Posts: 1,116
    Linux is all about choice. If you like the way one distro sets things up and what it includes, then that is your distro. Each distro has its following. If a distro doesn't live up to its claims, it loses popularity and the users move on, but, I won't disparage any well maintained distro, even if its derived from another distro. (Hmm, how many times can I use the word distro in one sentence? ... Now that was too many distros).
  • I guess you're right, it depends on taste, Some prefer fedora and some debian, When no one controls the development, it starts organizing itself. Unfortunately it is not always optimal.
  • benben Posts: 135
    You need to pay to get an official RHEL with a subscription, CentOS offers you the same thing (without a subscription) for free, they're slightly different but you will not notice hard changes between them.
    If you're studying for RHCE you may use CentOS for exercises and exams as well
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