Introduce some operating systems—CentOS system

CentOS system

CentOS, one of the Linux distributions, is a free, open source, redistributed open source operating system.

The CentOS Linux distribution is a stable, predictable, manageable and reproducible platform compiled from source code released by Red Hat Enterprise Linux (RHEL) in accordance with the Open Source Code.

Since $2004$ 3 $Since March$ , CentOS Linux has beencommunity-drivenopen source project designed to be functionally compatible with RHEL.

Background

CentOS is the abbreviation of Community Enterprise Operating System, also known as the community enterprise operating system. It is a recompiled version of Red Hat Enterprise Linux (RHEL), the leading enterprise Linux distribution, and has fixed many known bugs on the basis of RHEL.

CentOS is free, and you can use it to build an enterprise-level Linux system environment like RHEL, but you don't need to pay any fees to RedHat. CentOS technical support is mainly through the community's official mailing lists, forums and chat rooms.

Each version of CentOS is supported for ten years, and new versions of CentOS are released approximately every two years. Each version of CentOS is regularly updated to support new hardware .

Through this, a safe, low-maintenance, stable, highly predictable, and highly repeatable Linux environment is established.

CentOS history

Among Red Hat's products, there are RedHat Linux and the enterprise-oriented version Red Hat Enterprise Linux, which can be obtained and used free of charge through network FTP . However, in 2003, after redhat.com released redhat 9, it was no longer developed. Redhat 10, 11, fully turned to the development of redhat enterprise linux.

Different from the past, the new rhel 3 requires users to purchase lisence first, and redhat.com promises to ensure the stability and security of the product. The rhel 3 binary code is no longer available for download, but as part of the redhat service, but the source code is still open. Its project was replaced by the Fedora Project, and it was released under the name Fedora Core and provided free to ordinary users.

Fedora Core is a Linux distribution that is updated very quickly. A new version will be released in about half a year. This Fedora Core experiment has a strong charm. New features are added to it every time it is released, and the successful results obtained will be used in RHEL release in progress. Even so, unstable products that are frequently improved and updated are not the best choice for enterprises, and most enterprises will still choose paid RHEL products.

Most of the software packages that make up RHEL are released based on the GPL agreement, which is what we often call open source software. Because of this, Red Hat also follows this agreement and releases the software packages that make up RHEL publicly. It follows the GPL agreement, and anyone can re-develop and publish on the basis of the original software composition. CentOS is a Linux distribution that clones and reproduces the composition of RHEL based on the release of RHEL.

The clone version of RHEL is not only CentOS, but also White Box Enterprise Linux, TAO Linux and Scientific Linux. Although it is said to be a clone of RHEL, it is not exactly the same. The said clone has $100\%$ interchangeability. $100\%$ on CentOS $100%$ working.

The main function

CentOS can be understood as the community version of the Red Hat AS series, which is completely released after the improvement of Red Hat AS. There is no difference in various operations, usage and RHEL.
CentOS is completely free, and there is no problem that RED HAT AS needs a serial number.
CentOS's unique yum command supports online upgrades, which can update the system in real time, unlike RHEL, which requires money to purchase support services.
CentOS fixed many RHEL BUG.
CentOS Release Notes: CentOS3.1 is equivalent to RED HAT AS3 Update1 CentOS3.4 is equivalent to RED HAT AS3 Update4 CentOS4.0 is equivalent to RED HAT AS4.

Source code overview

Licensing Agreement: Open Source

OS: Linux

Official website: http://www.centos.org/

Source code download: http://isoredirect.centos.org/centos/5/isos/i386/

Common commands

ls: List the files and subdirectories under the current directory.

cd: Switch working directory.

pwd: Display the current directory.

mkdir: Create a new directory.

rm: Delete a file or directory.

cp: Copy a file or directory.

mv: Move a file or directory, and can also be used to rename a file or directory.

cat: View file content or combine multiple files into one file.

grep: Search the file for a string matching the specified pattern.

find: Search for files in the specified directory.

chmod: Modify the permissions of a file or directory.

chown: Modify the owner of a file or directory.

chgrp: Modify the group to which a file or directory belongs.

tar: Pack and unpack files.