What is YUM?

YUM (Yellowdog Updater Modified) is an open-source command-line as well as a graphical based package management tool for RPM (RedHat Package Manager) based Linux systems. It allows users and system administrators to easily install, update, remove or search software packages on a system. It was developed and released by Seth Vidal under GPL (General Public License) as an open-source, which means anyone can be allowed to download and access the code to fix bugs and develop customized packages. YUM uses numerous third-party repositories to install packages automatically by resolving their dependencies issues.

Following example, usages show the most commonly used options for performing package installation with yum :

Install a Package with YUM

To install a package called Firefox, just run the below command it will automatically find and install all required dependencies for Firefox.

# yum install firefox

Loaded plugins: fastestmirror
Dependencies Resolved

===================================================================================================================================================================================================================
Package Arch Version Repository Size
===================================================================================================================================================================================================================
Installing:
firefox x86_64 68.6.0-1.el7.centos updates 94 M

Transaction Summary
===================================================================================================================================================================================================================
Install 1 Package

Total download size: 94 M
Is this ok [y/d/N]: y
Downloading packages:
firefox-68.6.0-1.el7.centos.x86_64.rpm | 94 MB 00:03:04
Installing : firefox-68.6.0-1.el7.centos.x86_64 1/1
Verifying : firefox-68.6.0-1.el7.centos.x86_64 1/1

Installed:
   firefox.x86_64 0:68.6.0-1.el7.centos

Complete!

The above command will ask confirmation before installing any package on your system. If you want to install packages automatically without asking any confirmation, use option -y as shown in the below example.

# yum -y remove firefox

Removing a Package with YUM

To remove a package completely with their all dependencies, just run the following command as shown below.

# yum remove firefox.x86_64

Loaded plugins: fastestmirror
Dependencies Resolved

=========================================================================================================================================================
Package Arch Version Repository Size
=========================================================================================================================================================
Removing:
firefox x86_64 68.6.0-1.el7.centos @updates 230 M

Transaction Summary
=========================================================================================================================================================
Remove 1 Package

Installed size: 230 M
Is this ok [y/N]: y

Running transaction
Erasing : firefox-68.6.0-1.el7.centos.x86_64

Verifying : firefox-68.6.0-1.el7.centos.x86_64 1/1

Removed:
      firefox.x86_64 0:68.6.0-1.el7.centos

Complete!

Same way the above command will ask confirmation before removing a package. To disable confirmation prompt just add option -y as shown in below.

# yum -y remove firefox

Upgrading a Package using YUM

We can also upgrade any installed package to the latest stable version. For e.g. we’ve to upgrade the version of vsftd. Just run the following command it will automatically resolve all dependencies issues and install them.

# yum upgrade vsftpd

Loaded plugins: fastestmirror
Dependencies Resolved

==========================================================================================================================================================
 Package  Arch  Version  Repository  Size
==========================================================================================================================================================
Updating:
 vsftpd   i386  2.0.5-24.el5_8.1  updates  144 k

Transaction Summary
==========================================================================================================================================================
Install       0 Package(s)
Upgrade       1 Package(s)

Total size: 144 k
Is this ok [y/N]: y
Downloading Packages:
Transaction Test Succeeded
Running Transaction
  Updating       : vsftpd                                                                     1/2
  Cleanup        : vsftpd                                                                     2/2

Updated:
  vsftpd.i386 0:2.0.5-24.el5_8.1

Complete!

Downgrading a Package using YUM

There will be occasions when a program update may have lead to an unstable system due to hardware compatibility issues. For this or whatever the reason, if you want your previous version program back, you need to know how to downgrade the applications.

# yum downgrade httpd-2.2.3-22.el5

Dependencies Resolved

====================================================================================================================================================
Package Arch Version Repository Size
====================================================================================================================================================
Installing:
httpd i386 2.2.3-22.el5 rhel-i386-server-5 1.2 M
Removing:
httpd i386 2.2.3-31.el5 installed 3.1 M
Removing for dependencies:
httpd-manual i386 2.2.3-31.el5 installed 3.4 M
mod_ssl i386 1:2.2.3-31.el5 installed 173 k

Transaction Summary
====================================================================================================================================================
Install 1 Package(s)
Update 0 Package(s)
Remove 3 Package(s)

Total download size: 1.2 M
Is this ok [y/N]:

List Packages using YUM

Use the list function to search for the specific package with name, recently installed, updates available, etc. For example, to search for a package called OpenSSH, use the command.

# yum list openssh

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.mirrors.estointernet.in
* extras: centos.mirrors.estointernet.in
* updates: centos.mirrors.estointernet.in
Installed Packages
openssh.x86_64        7.4p1-21.el7       @anaconda

To list all the installed packages in a system, use the following command.

# yum list installed

To list all recently installed packages, use the following command.

# yum list recent

Use the following command to list the packages with updates available.

# yum list updates

Search for a Package using YUM

If you don’t remember the exact name of the package, then use search function to search all the available packages to match the name of the package you specified. For example, to search all the packages that match the word .

# yum search firefox

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.excellmedia.net
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
=================================================== N/S matched: firefox =============================================================
firefox.i686 : Mozilla Firefox Web browser
firefox.x86_64 : Mozilla Firefox Web browser

Get Information of a Package using YUM

Say you would like to know the information about a package before installing it. To get information about a package just issue the below command.

# yum info firefox

Loaded plugins: fastestmirror
* base: centos.excellmedia.net
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
Available Packages
Name : firefox
Arch : i686
Version : 68.6.0
Release : 1.el7.centos
Size : 97 M
Repo : updates/7/x86_64
Summary : Mozilla Firefox Web browser
URL : https://www.mozilla.org/firefox/
License : MPLv1.1 or GPLv2+ or LGPLv2+
Description : Mozilla Firefox is an open-source web browser, designed for standards compliance, performance and portability.

List all Dependencies of a Package using YUM

You can check the list of all Dependencies required by a specific package using the following command.

# yum deplist vsftpd

Loaded plugins: fastestmirror
* base: mirrors.praction.in
* extras: mirrors.praction.in
* updates: mirrors.praction.in
package: vsftpd.x86_64 3.0.2-25.el7
dependency: /bin/bash
provider: bash.x86_64 4.2.46-33.el7
dependency: /bin/sh
provider: bash.x86_64 4.2.46-33.el7
dependency: libc.so.6(GLIBC_2.15)(64bit)

Yum Provides Function

Yum provides function is used to find which package a specific file belongs to. For example, if you would like to know the name of the package that has the /etc/ssh/sshd_config.

# yum provides /etc/ssh/sshd_config

Loaded plugins: fastestmirror
* base: centos.excellmedia.net
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
openssh-server-7.4p1-21.el7.x86_64 : An open source SSH server daemon
Repo : base
Matched from:
Filename : /etc/ssh/sshd_config

openssh-server-7.4p1-21.el7.x86_64 : An open source SSH server daemon
Repo : @anaconda
Matched from:
Filename : /etc/ssh/sshd_config

Check for Available Updates using Yum

Find how many installed packages on your system have updates available, use the following command to check.

# yum check-update

Update System using Yum

To keep your system up-to-date with all security and binary package updates, run the following command. It will install all the latest patches and security updates to your system.

# yum update

List all available Group Packages

In Linux, number of packages are bundled to a particular group. Instead of installing individual packages with yum, you can install a particular group that will install all the related packages that belong to the group. For example to list all the available groups, just issue following command.

# yum groups list

Loaded plugins: fastestmirror
* base: centos.excellmedia.net
* extras: centos.mirror.snu.edu.in
* updates: centos.mirror.snu.edu.in
Available Environment Groups:
Minimal Install
Compute Node
Infrastructure Server
File and Print Server
Basic Web Server
Virtualization Host
Server with GUI
GNOME Desktop
KDE Plasma Workspaces
Development and Creative Workstation
Available Groups:
Compatibility Libraries
Graphical Administration Tools
Security Tools
System Administration Tools

Install a Group Packages

Install a particular package group, use option groups install. For example, to install “Development Tools“, execute the below command.

# yum groups install "Development Tools"

Update a Group Packages

To update any existing installed group packages, just run the following command as shown below.

# yum groups update 'DNS Name Server'

Get details of a Group Packages

Display details about a group of packages from the system, just use the below command.

yum groups info "System Administration Tools"

Remove a Group Packages

Delete or remove any existing installed group from the system, just use the below command.

#yum groups remove 'DNS Name Server'

List Enabled Yum Repositories

Get the list of all enabled Yum repositories in your system, use following command.

# yum repolist

Loaded plugins: fastestmirror
* base: centos.excellmedia.net
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
repo id                          repo name                                          status
base/7/x86_64                CentOS-7 - Base                                        10,097
extras/7/x86_64              CentOS-7 - Extras                                         341
updates/7/x86_64             CentOS-7 - Updates                                      1,787
repolist: 12,225

List all Enabled and Disabled Yum Repositories

The following command will display all enabled and disabled yum repositories on the system.

# yum repolist all

Interactive Yum Shell

Yum utility provides a custom shell where you can execute multiple commands.

# yum shell

Loaded plugins: fastestmirror
> search named
Loading mirror speeds from cached hostfile
* base: centos.excellmedia.net
* extras: centos.excellmedia.net
* updates: centos.excellmedia.net
======================================================== N/S matched: named =================================================================
pcp-pmda-named.x86_64 : Performance Co-Pilot (PCP) metrics for Named
bind-chroot.x86_64 : A chroot runtime environment for the ISC BIND DNS server, named(8)
bind-sdb-chroot.x86_64 : A chroot runtime environment for the ISC BIND DNS server, named-sdb(8)

Name and summary matches only, use "search all" for everything.
>

Clean Yum Cache

By default yum keeps all the repository enabled package data in /var/cache/yum/ with each sub-directory, to clean all cached files from enabled repository, you need to run the following command regularly to clean up all the cache and make sure that there is nothing unnecessary space is using.

# yum clean all

View History of Yum

To view all the past transactions of yum command, just use the following command.

# yum history

Loaded plugins: fastestmirror
ID | Login user | Date and time | Action(s) | Altered
-------------------------------------------------------------------------------
8 | root <root> | 2020-04-06 13:09 | Install | 1
7 | root <root> | 2020-04-06 12:15 | Install | 31
6 | root <root> | 2020-04-06 12:02 | Erase | 1 EE
5 | root <root> | 2020-04-06 11:43 | Install | 1
4 | root <root> | 2020-04-06 11:39 | Erase | 1 EE
3 | root <root> | 2020-03-30 17:17 | Install | 84
2 | root <root> | 2020-03-30 17:15 | Install | 1
1 | System <unset> | 2020-03-30 16:50 | Install | 301
history list

The post Yum Commands Cheat Sheet for RHEL appeared first on Armour Infosec.

What is YUM?

YUM (Yellowdog Updater Modified) is an open-source command-line as well as a graphical based package management tool for RPM (RedHat Package Manager) based Linux systems. It allows users and system administrators to easily install, update, remove or search software packages on a system. It was developed and released by Seth Vidal under GPL (General Public License) as an open-source, which means anyone can be allowed to download and access the code to fix bugs and develop customized packages. YUM uses numerous third-party repositories to install packages automatically by resolving their dependencies issues.

General Configuration file of yum is located at /etc/yum.conf
You can see this file with any editor

Installation of Yum Server with local repository

We can install a local repository for YUM with DVD/ISO file. If you have DVD then Copy the entire Linux OS DVD’s content to Hard-drive. Insert DVD into DVD-RW and go to the mounting point of DVD.

To make a directory (folder) on root.

[root@localhost ~]# cd /
[root@localhost /]# mkdir rhel7

To go on the mounting point of DVD. cd [Mounting Location]

[root@localhost ~]# cd /run/media/root/rhel-server-7/

Copy all entire Linux OS DVD’s into /rhel7 directory (folder)

If you have an iso file of Rhel OS then follow how to mount ISO image in rhel.
Go where there you have copied the entire OS DVD. To go on the Packages Directory. Then Install the createrepo package. To install package

It gives dependencies error. Then you have install depend packages

# rpm -ivh deltarpm-*
# rpm -ivh python- deltarpm-*

Then you have to again install the createrepo package

To make “Createrepo” Database for the local repository which is used for YUM. Go to packages directory which is copied already. Go to the location of packages.

Create repo database

Or

Create a file with repo as an extension and specify the YUM details in /etc/yum.repos.d directory (folder)

yum.repos.d this is a directory which contains all repository. now we create our new repo with any editor.

# vim rhel.repo
[RHEL]
name=local_repo
baseurl=file:/rhel7/Packages/
:wq!

[rhel] :- Title of yum repo,
name=rhel  :- name of yum repo
baseurl=file:/rhel7/Packages/ :- location of Rpm packages
gpgcheck=0 :- verify rpm to RPM-GPG-key (gpgcheck=0 Disabal, gpgcheck=1 Enable)

Now we can create successful YUM repository, Verify run the yum command

# yum check
# yum repolist all

Yum Commands Cheat Sheat

Click here to go the blog.

The post What is YUM ? How to Install YUM in Linux ? appeared first on Armour Infosec.