What is CentOS?

Linux is an acronym for Gnu/linux, usually referred to as a generic term for various Linux distributions.
The common Linux manufacturers mainly have Redhat/novell and so on.

Redhat has two major Linux product lines, one of which is the free Fedora Core series
Primarily for desktop editions, providing support for more new features.
Another product line is the enterprise series of charges, which is divided into: As/es/ws and other branches.

Advanced Server, abbreviated as AS. As on the basis of the standard Linux kernel,
Performance enhancements, increased reliability, and integrated drivers for many common servers.
Devices such as disk-array cards for common rack servers such as IBM/DELL/HP can be easily identified.

As major version 2.x/3.x/4.x, which is what we call As3/as4
There are several upgrades for each version, such as the earliest AS4, and some updates have been encountered
At this point will be released AS4 Update1, in the future there will be AS4 Update2/update3 and other appear
Referred to as AS4U1/AS4U2/AS4U3. This is very similar to Microsoft's release form,
Microsoft's Windows NT4 from SP1 out to sp6,windows2000 from SP1 to SP4 ....

As these update versions contain a different version of the main package, it is best not to mix
Otherwise, the problem is very easy to come up with. Prima and Plesk's installation packages are designed for a variety of distributions
On the download page, it is usually identified by which versions and which update systems are supported.

ES, is a lite version of AS. The difference between him and the common as series is that as supports up to 4 CPUs,
And ES can only support two CPUs. As and Es are no different on most packages,
Only a few packages on the kernel are different.
The price difference between as and ES is larger, usually es used in the OEM version purchased with the server
For example, if you purchase a Dell server, the Linux pairing will be the ES series.
If you want to match the as series, you need to spend thousands of yuan more.

WS, is a further simplified version of ES, mainly for the Enterprise internal desktop office market, less domestic use.

Redhat's Fedora Core Linux and Enterprise Linux are subject to the GNU protocol
That is, you need to publish your own source code.
So, for free Fedora Core Linux, you can download the ISO disc directly from the Redhat website,
It can also be downloaded to the srpm ISO, which is the package source CD.
For paid Enterprise Linux series, is a commercial product, so the website can not be downloaded to the ISO file,
You need to purchase a duly authorised party.
Because Enterprise Linux also needs to follow the GNU protocol, the source code must be published.
So on the Redhat website, you can get the AS/ES/WS series of srpm source ISO files.
These files can be downloaded freely, modify the code, and recompile the use.

A project called Community Enterprise Operating System was born.
His initials are both CentOS. The CentOS community downloads all the source code on Redhat's website,
to recompile. After recompilation, since AS/ES/WS is a commercial product,
All Redhat logos and logos must be changed to their own CentOS logo.
For example, the AS4 original srpm source code compiled, it became the CentOS 4.0.
After compiling the source code of AS4UPDATE1, it becomes the CentOS4.1.
After compiling the source code of As4update2, it becomes the CentOS4.2.
Similarly, the 3.x/4.x of CentOS corresponds to the corresponding version.

So we say that CentOS is the free version of Redhat's as/es/ws.
With CentOS, you get the same performance and feel as as/es.
In addition to providing the standard number 1~4 or several ISO-
Server discs with a minimum of 1CD are also available. Install the system with the server CD-ROM,
is a minimal Linux kernel plus a common httpd/mysql package.
Does not contain software that is useless for servers such as Xwindows desktops.

Prima, Plesk, Virtuozzo and both can be installed on the CentOS.

What is CentOS?