Introduction and use of the second--yum of package Manager

First, preface

Before we introduced the application of RPM (see http://windchasereric.blog.51cto.com/5419433/1676324 for details), we found that the RPM installation software has a very tedious problem, that is the dependency between package and package, If you want to install and use the software program properly, you must resolve the dependencies of the software step-by-step as required. Then if the program uses a lot of packages, it will be very expensive to use people's time and energy. So is there a way to solve this problem?

In RPM we introduce the RPM software that records installation information between the software, which also includes the dependency properties between the software. So if we analyze this list before the installation, then we can install the required software one at a time according to the relationship between the software, so as to solve this problem, this is the mechanism of YUM.

Ii. introduction of Yum

Yum (Yellow dog Updater Modified) is a pre-RPM package Manager in CentOS that downloads rpm packages from a specified server and automatically analyzes and processes the dependencies between RPM packages, and then installs the packages that depend on them in turn, Without the hassle of one installation.

Third, Yum Repository:yum Warehouse

Components of the Yum Warehouse

3.1. Data

Contains all the package files

3.2. Meta-data

Refers to a data file: includes the package name of each package, the version information, the list of files contained in each package, the dependencies between packages and packages, and the grouping information for packages.

Small extension: How does metadata come about? Using the Createrepo tool, we can quickly and concisely read out all the RPM package information in the directory where we have specified a large number of RPM packages, analyze his dependencies and generate metadata.     So Createrepo can understand it as a tool for making yum metadata. In the CD actually also have this metadata, the path in the CD-ROM [[email protected] mnt]# CD repodata/, followed by the SQLite file suffix notes: centos5 is the XML suffix, CENTOS6, 7 is the SQLite database The way to store the

Iv. Introduction to Yum configuration files

Yum profiles are in 2: Master profile + Warehouse configuration file

4.1. Master Profile Path/etc/yum.conf

    [main]        cachedir=/var/cache/yum/$ basearch/$releasever       #下载RPM包的缓存目录     keepcache=0                                           #RPM缓存的程序包安装完成后是否保存, 0 means no save, 1 means save     buglevel=2                                           #调试级别   Value range  0 - 10, default value is 2        logfile=/var/log/yum.log                             #yum相关日志存放路径     exactarch=1                                          #是否要平台完全匹配才能安装      obsoletes=1                                          #需不需要检查已过期的仓库     gpgcheck=1                                          # Whether to check package integrity and legality     plugins=1                                            #是否允许支持yum的插件功能,0  said that  ,1 is not allowed, it is recommended to allow, General will use yum-fastestmirror this plugin                 installonly_limit=5                                # How many kernel packs are allowed to be retained     bugtracker_url=http://bugs.centos.org/set_project.php?project_id=16&ref= Http://bugs.centos.org/bug_report_page.php?category=yum    distroverpkg=centos-release                          #指定一个软件包,yum  will determine your distribution based on this package, either by default, Redhat-release, or by installing any rpm  packages for your own distribution.

4.2. Warehouse configuration file path /etc/yum.repos.d/*.repo

The warehouse file can have multiple, and the configuration information of one or several related warehouses can be saved as a file, and so the warehouse file name ends in. Repo

[repoid]              #容器名字, must be the only name=                  #some  name The name of the  for this repository warehouse, only one identification baseurl=               #指定真正仓库所在的路径, can refer to multiple warehouses                           #例如: Baseurl=file:///media/cdrom                          #      ftp://172.168.1.1/path      #备注第二行不能顶格写, or it will go wrong mirrorlist=          # List containers can use the site, if you do not want to use, you can add  #  comment enabled= {0 | 1}      #指是否启用这个仓库 , 0 means not enabled, 1 means enable GPGCHECK= {0&Nbsp;| 1}     #是否要检测软件包的合法性, 0 means no detection, 1 means no check gpgkey=                #软件包的公钥文件所在路径, for example: gpgkey=file:///media/cdrom/ gpg-rpm-key-centos-6cost=                  #仓库优先级, for example, if a package is available in multiple warehouses, which installation should I choose? By this priority, the default is 100, the smaller the number, the higher the priority.

Note: The default usage for each warehouse:

Base library: A package (CD-ROM) typically provided for the system release

Updates library: Storing update packages

Extra library: Storing extra bags

Epel Library: Epel library file

The library itself has priority, but only in the client, the server side is no priority

Tip: Yum can support multiple protocols, including FTP, HTTP, NFS, and local file sharing services

So the BaseURL in the warehouse configuration file can be written in more than one format.

1) FTP

Format: ftp://server/path/to/repository

2) HTTP

Format: http://server/path/to/repository

3) NFS

Format: Nft://server/nfs_path

4) Local file sharing service

Format: file:///path/to/repository

Five, yum installation steps

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Vi. use of the Yum command

6.1. Yum Query function

Yum [option] [information that needs to be queried] [parameters]

-y: The default Yum needs to be interactive mode, and-y indicates that the Yes response is provided automatically

Search: Searching for a software name or keyword

List: Lists all the packages and names managed by Yum

Info: Ditto, also similar to Rpm-qai

Provides: Find this command is generated by software installation, similar to RPM-DF features

Repolist: List all available repo

For example: [[email protected] ~]# Yum provides bash

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[email protected] ~]# Yum repolist

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6.2, install, upgrade, downgrade, uninstall function

Yum [option] [information that needs to be queried] [parameters]

Install: Follow the required software

Reinstall: Back up the software that needs to be reinstalled

Update: Next to the software you need to upgrade to

Check-update: Check for available upgrade packages

Downgrade: Back to the version you need to downgrade to

Remove: Uninstalling the Software

Erase: Function ditto, uninstall

For example: [[email protected] yum.repos.d]# Yum install zlib-static

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6.3. Functions related to software groups

Yum [group function] [software group]

Grouplist: List all available groups

GroupInfo: followed by group name, which can be used to understand the group contains the names of all groups

Groupinstall: Installing the entire set of software

Groupremove: Deleting software for a group

 for example: [[email protected] yum.repos.d]# yum grouplist# All package groups are not listed, if you want to install a group can be installed directly using Groupinstall installed groups:              #已经安装的软件组    Additional Development   Base    console internet tools   development toolsinstalled language  Groups:    #已经安装的语言组    Arabic Support [ar]    armenian support [hy]   georgian support [ka]available groups:              #有效软件组包文件    Backup  client       backup serveravailable language groups:     #有效的语言组包文件    Afrikaans Support [af]   Albanian  SUPPORT [SQ] 

6.4. Clean up the cache

Yum Clean {All | package | headers}

All: Delete all data, including meta data and software files

Package: Remove all downloaded software files

Headers: Delete all downloaded meta data files

For example [[email protected] yum.repos.d]# Yum clean all #这样将会清除所有的已下载的元数据和软件文件Loaded plugins:fastestmirror, securitycleaning Repos:base Extras updatescleaning up everythingcleaning up list of fastest mirrors

Vii. Summary of Knowledge

7.1. Yum is the front-end tool for RPM packages, which mainly solves the dependencies of packages

7.2. Need to know the Yum configuration file

Master profile/etc/yum.conf and warehouse configuration file /etc/yum.repos.d/*.repo

7.3. Yum press and hold function process

7.4. Yum commands

Install, uninstall, update, program group, clean cache, query and other functions

This article is from the "Crab Learn Linux" blog, please be sure to keep this source http://windchasereric.blog.51cto.com/5419433/1676777

Introduction and use of the second--yum of package Manager