Software package management commands in CentOS

In CentOS and FedoraCore releases, a comprehensive management tool called yum software package is used. its full name is Yellowdog.

Software package management in CentOS-yum

★YUM introduction
In CentOS and Fedora Core releases, a comprehensive management tool called yum software package is used. its full name is Yellowdog Updater and Modified. This tool is not developed by CentOS, it is a comprehensive software package management tool developed by Yellow Dog Linux. As a software package integrated management tool, in addition to yum, there are also the up2date used by DebianGNU/Linux APT and Red Hat Enterprise Linux.
Their common features are:

* Install and upgrade software packages through the network
* Automatically solves dependencies between software packages.
Note that the Yum software package upgrade package is not the latest software package, but the software package confirmed by CentOS, which can be well integrated with the system in CentOS, for updates to the latest software packages, see software package management under CentOS-rpm

★Yum usage preparation
Before using yum, the most basic thing is to first import the GPG public key, and change the website where the software package is downloaded (the software package defined in the yum configuration file ).

GPG public key
The RPM software package has an electronic signature. this electronic signature is used to determine whether the software package has been tampered with, whether the data has been damaged, and whether the data is complete. in this way, it is necessary to import the GPG public key of the development organization's configuration. Then this GPG public key can be obtained from the package release site and CD-ROM/DVD-ROM, which is installed by default in/usr/share/doc/centos-release-4/RPM-GPG-KEY under the system, there is also an identical file/usr/share/doc/centos-release-4/RPM-GPG-KEY-centos4. If you only use the centos.org image site, this public key is imported by default. you can see on our website that when the unofficial library is used, we also imported this GPG public key, referring to the operation of defining unofficial libraries under the http://www.centospub.com/make/newenv.html.
★How to import the public key of GPG:
# Rpm-import GPGkey path or network file

★Update the image download address of a software package.
Cent0S images are distributed in many parts of the world. the default setting is centos.org. China images are distributed in Shanghai, Hong Kong, and Fujian. You can modify the software package download image site to speed up software package download.
The setting file for Yum is/etc/yum. repos. d/CentOS-Base.repo. For site changes, refer to the Chao moderator's "CentOS has a Chinese image at last !" .
Here, users who want to change the file settings are reminded to back up the original file before modifying it, or comment out the original file content instead of deleting or overwriting the original settings, and add comments in the file, such as the time when the changes were made, who made the changes, and the changed content, which is good for system management and maintenance.

★Update system and software using yum
In the configuration explanation on this site, we have seen many times that we have used yum to install software.
For details about how to use yum, refer to the documentation on using the yum management software of fedore.clinux.org.

★Common yum parameter options
Usage
Example:
# Yum check-update
# Yum remove package name
# Yum install package name
# Yum update package name

Option

Description
Check-update: displays the software packages that can be upgraded
Clean deletes the downloaded old header. Same as clean all
Clean oldheaders delete old headers
Clean packages delete the downloaded package
Info Display available package information
The info package name displays the specified package information.
Install package name install the specified package
List show available software packages
List installed displays installed software packages
List updates displays the software packages that can be upgraded
Provides package name displays the files contained in the package
Remove the software package name to delete the specified software package and confirm the dependency of the specified software package.
Search keywords use keywords to search for software packages. The search object is RPM file name, Packager (package), Dummary, and Description.
Update all the software packages that can be upgraded
Update the software package name to upgrade the specified software package

Option

Description
Groupinstall install the specified group
Update group member software packages installed by groupupdate
A list of installed groups and groups that can be installed by grouplist is displayed.
Groupremove deletes a specified group.
Groupinfo: displays the packages included in the specified group.