Introduction to CentOS and RedHat Linux

Time:2021-9-16

Introduction to CentOS
CentOS is the abbreviation of community enterprise operating system. Many people call it community enterprise operating system. No matter what you call it, it is a distribution version of Linux operating system.
CentOS is not a new Linux distribution. It seems that everyone has heard of red hat. There are enterprise products in the red hat family. It is Red Hat Enterprise Linux (hereinafter referred to as RHEL), and CentOS is the cloned version of RHEL. RHEL is a Linux distribution adopted by many enterprises. It can be used only after paying red hat, and can get paid services, technical support and version upgrade. CentOS can build a Linux system environment like RHEL, but it does not need to pay any product and service fees to red hat. At the same time, it does not get any paid technical support and upgrade services.

Red hat’s products include Red Hat Linux (such as redhat8,9) and Red Hat Enterprise Linux, which can be obtained and used for free through network FTP. However, in 2003, Red Hat Linux stopped publishing and its project was replaced by Fedora project, It is distributed under the name of Fedora Core and provided to ordinary users for free. The Fedora Core Linux distribution is updated very quickly, and a new version will be released in about half a year. The current version is Fedora Core 6. This Fedora Core test has a strong flavor. New functions are added to each release, and the successful results will be adopted in the release of Dao RHEL. In spite of this, unstable products that are frequently improved and updated are not the best choice for enterprises. Most enterprises will still choose paid RHEL products (which has a deep meaning, for example, enterprises make money with Linux, return the money to enterprises, circulate funds among enterprises, return to the society, improve service standards, etc.).

Most of the software packages that constitute RHEL are released based on GPL protocol, which is what we often call open source software. Because of this, red hat also follows this Agreement and publishes the software package constituting RHEL. As long as it follows the GPL agreement, anyone can redevelop and publish on the basis of the original software composition. In this way, CentOS reproduces the composition of RHEL as a Linux distribution based on the release of RHEL. RHEL’s clone version is not only CentOS, but also white box Enterprise Linux, Tao Linux and scientific Linux (I haven’t heard of anything else, have I?).

Although it is as like as two peas of RHEL, it is not exactly the same. The cloned clone has 100% interchangeability. However, it does not guarantee that the software corresponding to RHEL can work 100% normally on CentOS. In addition, for the paid services and technical support of RHEL, the correction of security vulnerabilities and the upgrading of software packages are delayed for days, weeks and months (in fact, it is not very slow).

CentOS features
In the full name of CentOS, we can see enterprise OS, that is, enterprise system. This enterprise system is not an enterprise level system, but it can provide the elements required by enterprise level applications.
For example:
Stable environment
Long term upgrade support
Strong conservatism
Large scale systems can also play a good performance
CentOS meets the above elements, and fedora is the distribution that meets the above elements. Fedora is very similar to CentOS, but for CentOS, Fedora provides more new functions and software, fast release and update, which adds a lot of work in stability and management. The system environment required by the enterprise should be an efficient and stable system environment that can be used for a long time after one-time construction. Therefore, the frequently updated and released system environment like Fedora does not correspond to the application of the enterprise. On the other hand, CentOS can meet the needs of the above enterprises. Among the many cloned versions of RHEL, CentOS is very outstanding and excellent.

Differences between CentOS and RHEL
In fact, why CentOS? What is the relationship between CentOS and RHEL?
RHEL is released in two ways. One is binary distribution, the other is source code distribution.
Either way, you can get it for free (for example, download it from the Internet) and publish it again. But if you use their online upgrades (including patches) or consulting services, you have to pay.
RHEL always provides source code distribution. CentOS compiles the source code distributed by RHEL once again to form a usable binary version. Since the source code of Linux is GNU, it is legal from obtaining the source code of RHEL to compiling it into a new binary. Only RedHat is a trademark, so the RedHat trademark must be removed in the new distribution.
RedHat’s attitude towards this distribution is: “we are not opposed to this distribution. For users who really pay to us, what they pay attention to is not the system itself, but the business services we provide.”
Therefore, CentOS can get all the functions of RHEL, even better software. However, CentOS does not provide commercial support to users, and of course, it does not bear any commercial responsibility.
I’m gradually transferring my RHEL to CentOS because I don’t want to pay for RHEL upgrade. Of course, this is because I have many years of UNIX experience, so RHEL’s commercial technical support is not important to me.
However, if you are a pure business enterprise, I suggest you buy RHEL software and corresponding services. In this way, you can save your IT management expenses and get professional services.
In a word, whether you choose CentOS or RHEL depends on whether your company has the corresponding technical force.

supplement
1. CentOS also fixed some as bugs, such as package selection during installation
2. CentOS added Yum online upgrade
3、
CentOS-3.1 = AS3-update1
CentOS-3.2 = AS3-update2
CentOS-3.3 = AS3-update3
CentOS-3.4 = AS3-update4
CentOS-3.5 = AS3-update5
CentOS-4.0 = AS4
CentOS-4.1 = AS4-update1
4. Using CentOS is completely legal and does not involve copyright issues
5. It is very convenient to obtain CentOS. More than 10 site images (HTTP / FTP) and BT mode (seeds are provided all year round) are provided all over the world.
CentOS (community enterprise operating system) is one of the Linux distributions. It recompiles the source code of Red Hat Enterprise Linux (mainly removing the red hat trademark). Why does red hat tolerate this behavior of CentOS? CentOS downloads the source code from the red hat server, compiles it, and distributes it free of charge. It does not provide paid commercial support. Red hat releases an upgrade patch, and CentOS will release the patch in a few hours or at most a few days. CentOS is completely legal, and red hat is helpless. Its business is based on the open source model. However, CentOS is indeed swallowing the red hat Market, which can also be observed from google trends. Judging from the current situation, the damage caused by CentOS has not reached the point where red hat has to change its business model. The advantage is that it forces red hat to accelerate innovation and keep it ahead of other Linux server distributions. The real victims of CentOS’s great success are other distributions, such as Novell’s sles and Ubuntu server.

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