Yum (full name: Yellow dog Updater, Modified) is a Shell front-end package manager in Fedora, RedHat and CentOS. Based on RPM package management, it can automatically download and install RPM packages from the specified server, automatically handle dependencies, and install all dependent software packages at one time without cumbersome downloading and installation at one time.

yum syntax

1	yum [options] [command] [package ...]

• Options: optional. The options include - h (help), - y (select "yes" when prompted by the installation process), - q (do not display the installation process), etc.
• command: the operation to be performed.
• The object of the package operation.

option

-h: Display help information;
-y: Answer "yes" to all questions;
-c: Specify the configuration file;
-q: Quiet mode;
-v: Detailed mode;
-d: Set the commissioning level (0-10);
-e: Set the error level (0-10);
-R: Set the maximum waiting time for yum to process a command;
-C: Run completely from the cache without downloading or updating any header files.

parameter

#Regular orders
install: install rpm Software package;
update: to update rpm Software package;
check-update: Check for updates available rpm Software package;
remove: Delete the specified rpm Software package;
list: Display the information of the software package;
search: Check the information of the software package;
info: Displays the specified rpm Description and summary information of the software package;
clean: clear yum Expired cache;
shell: get into yum of shell Prompt;
resolvedep: display rpm Dependency of software package;
localinstall: Install local rpm Software package;
localupdate: Show local rpm Update the software package;
deplist: display rpm All dependencies of the package.

alias List or create command aliases
autoremove Remove all unneeded packages that were originally installed because of dependencies
check Find problems in the package database
check-update Check for software package upgrades
clean Delete cached data
deplist Lists the dependencies of software packages and the sources that provide them
distro-sync Synchronize installed packages to the latest available version
downgrade Degraded package
group Display or use group information
help Displays a helpful usage message
history Display or use transaction history
info Displays detailed information about a package or package group
install Install one or more software packages into the system
list Lists a package or group of packages
makecache Create metadata cache
mark Mark or unmark packages installed by users in installed packages.
module Interact with the module.
provides Find packages that provide the specified content
reinstall Reload a bag
remove Remove one or more software packages from the system
repolist Displays the configured software warehouse
repoquery Search for packages that match keywords
repository-packages Run the command on all packages in the specified repository
search Searches the package details for the specified string
shell Run interactive DNF terminal
swap Run interactive DNF Terminal to remove or install spec Description file
updateinfo Displays reference suggestions for the package
upgrade Upgrade one or more software packages in the system
upgrade-minimal Upgrade, but only the "latest" package has fixed problems that may affect your system

List of plug-in commands:
builddep Install build dependencies for package or spec file
changelog View the change log data of the software package
config-manager Administration dnf Configuration options and software warehouse
copr And Copr Warehouse interaction
debug-dump Dump installed RPM Package information to file
debug-restore Recover the software package record in the debug dump file
debuginfo-install Install and debug information package
download Download the package to the current directory
needs-restarting Determine whether the upgraded binary needs to be restarted
playground And Playground Warehouse interaction.
repoclosure Displays a list of unresolved dependencies in the warehouse
repodiff List the differences between the two sets of warehouses
repograph Output the complete software package dependency diagram in the form of dotted line diagram
repomanage Administration RPM Package directory
reposync Download all software packages in the remote warehouse

install

yum install # all
 yum install package1 # installs the specified package1
 yum groupinsall group1 # setup group1

Update and upgrade

Update # all using Yum or up2date
 Update package1 using Yum or up2date # to update the specified package1
 Yum check update # checks for updatable programs
 Upgrade package package1 using Yum or up2date # to upgrade the specified package package1
 yum groupupdate group1 # upgrade program group1

Find and display

yum info package1 # displays the installation package information
 yum list # displays all installed and installable packages
 yum list package1 # displays the installation of the specified package
 yum groupinfo group1 # displays program group1 information. yum search string searches for installation packages by keyword string

Delete program

yum remove |  Erase package1 # delete package1
 yum groupremove group1 # deletes the program group1
 Yum / up2date deplist package1 # to view program package1 dependencies

Clear cache

yum clean packages # clears the packages in the cache directory
 yum clean headers # clears headers in the cache directory
 Yum clean oldheads # clears old headers from the cache directory
yum clean all # clears all cache directories

Linux configuration yum source

Domestic yum source:

Ali: http://mirrors.aliyun.com

Netease: http://mirrors.163.com

China University of science and technology: http://mirrors.ustc.edu.cn/

View yum source configuration

cat /etc/yum.repos.d/CentOS-Base.repo

[base]           #Warehouse name
name=            #Warehouse description
mirrorlist=      #Warehouse image path
baseurl=         #Warehouse url path
enabled=         #Whether the warehouse is enabled. 1 means enabled and 0 means closed
gpgcheck=1       #Key detection: 1 means on, 0 means off
gpgkey=          #Check the address of the key. If it is not checked, this can be left blank

1. yum source configuration (Network):

1.1 back up the original yum source first:

[root@alliancehacker ~]# mkdir -p /root/back
[root@alliancehacker ~]# mv /etc/yum.repos.d/CentOS-Base.repo  /root/back/CentOS-Base.repo.back

1.2 download the new yum source (Alibaba):

// Because this is CentOS 8, the source chose centos-8 repo

[root@alliancehacker ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo

1.3 clear the original yum cache:

[root@localhost ~]# yum clean all

1.4 generate new cache:

[root@localhost ~]# yum makecache

1.5 add multiple network sources:

#stay /etc/yum.repo.d There are several folders in, and each folder is a source configuration file.#For example:
#(1) Local Repo (local source, name optional)
[local]
name=local
baseurl=file:///mnt/cdrom
gpgcheck=0
enabled=1
#(2) 163 Repo (source of 163)
[163]
name=163
baseurl=http://mirrors.163.com/centos/7.5.1804/os/x86_64/
gpgcheck=0
enabled=1
#It should be noted here that you need to go to the base URL http://mirrors.163.com/centos Here, find the directory of your corresponding redhat version, and then click os and x86_64 (usually), and then replace the baseurl above with the URL displayed on your address bar. Save and exit.

1.6 order supplement

I hope the following information can answer your question:
1. Query current repo (all, enabled, disabled)

yum repolist [all|enabled|disabled]

Install the software and specify the repo you do not want to use

yum –-disablerepo=repository-name install nagios

Install the software from the repo set to disabled (enabled=0)

yum --enablerepo=epel install nagios

In a repo setting, specify the package name you want to exclude

exclude=nagios

If there are multiple versions of one software in multiple repo s, you can specify the version during installation

yum install httpd-2.4.6-6

2. yum source configuration (local):

2.1 downloading ISO files

Download the full version of CentOS iso file from CentOS's official website and upload it to the Linux file system, such as / opt/tools /.

2.2 create a mount directory for ISO

1 mkdir /mnt/vcdrom

2.3 mount ISO files to the mount directory

mount -o loop -t iso9660 /opt/tools/CentOS-7-x86_64-bin-DVD1.iso /mnt/vcdrom

2.4 remove or back up the original yum source CentOS base Repo file

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.back

2.5 configuring CentOS media Repo file

[root@localhost ~]# cat /etc/yum.repos.d/CentOS-Media.repo 
[c7-media]
name=CentOS-$releasever - Media
baseurl=file:///MNT / vcrom / # change the baseurl to the mounting directory of the DVD
gpgcheck=0                            #Turn off key detection
enabled=1                             #Enable warehouse
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

2.6 clear the original yum cache:

[root@localhost ~]# yum clean all

2.7 generate new cache:

[root@localhost ~]# yum makecache

2.8 write script and automatically mount image after startup

[root@localhost ~]#vim /opt/shell/mymount.sh
#!/bin/bash
#
mount -o loop -t iso9660 /opt/tools/CentOS-6.7-x86_64-bin-DVD1.iso /mnt/vcdrom

2.9 modify script permissions:

[root@localhost ~]#chmod 777 /opt/shell/mymount.sh

2.10 modify / etc / RC Local configuration file, add / opt / shell / mymount. At the last line of the file sh

[root@localhost ~]#vim /etc/rc.local
/opt/shell/mymount.sh

2.11 server restart test:

[root@localhost ~]# reboot

Example 1: install php7 using yum or up2date

Reference: php7 3 install @ centos7

https://www.itgeeker.net/php7-3-yum-install-on-centos-7/

https://dl.fedoraproject.org/pub/epel/

http://rpms.remirepo.net/enterprise

Find your own version on this website and replace it. Some sources may become invalid. Find the available ones by yourself at that time

#Add several sources, otherwise an error will be reported
#The yum source address of php higher version has two parts, one of which is EPEL release and the other is from webtatic. If you skip EPEL release, when installing webtatic
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
rpm -Uvh http://rpms.remirepo.net/enterprise/remi-release-8.rpm

Install the extensions you want

yum --enablerepo=remi install php73-php php73-php-pear php73-php-bcmath php73-php-pecl-jsond-devel php73-php-mysqlnd php73-php-gd php73-php-common php73-php-fpm php73-php-intl php73-php-cli php73-php php73-php-xml php73-php-opcache php73-php-pecl-apcu php73-php-pdo php73-php-gmp php73-php-process php73-php-pecl-imagick php73-php-devel php73-php-mbstring php73-php-zip php73-php-ldap php73-php-imap php73-php-pecl-mcrypt

Run and view the version, restart the command, add automatic startup, and link php files

# The current PHP memory limit is below the recommended value of 512MB.
vi /etc/opt/remi/php73/php.ini
memory_limit = 512M

#If you are running nginx instead of apache, modify
vi /etc/opt/remi/php73/php-fpm.d/www.conf
user = apache
group = apache
# Replace the values with
user = nginx
group = nginx

Uninstall all php7 three

yum remove php73-php*