Normally, removing a package using YUM package management system will remove that package together with its dependencies. However, certain dependencies will not be removed on the system, these are what we can term as “unused dependencies” or (so-called “leaf packages” according to YUM man page).

In this article, we will explain two ways to remove or uninstall a package along with their dependencies using YUM package manager in CentOS and RHEL distributions.

1. Using YUM’s Autoremove Option

This method requires you to add the directive clean_requirements_on_remove in YUM’s main configuration file /etc/yum.conf. You can use your favorite command line editor to open it for editing as shown.

# vim /etc/yum.conf

Then add the following line to the /etc/yum.conf file as shown in the output below. A value of one indicates that the directive is enabled (or turned on), a zero means otherwise.

[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=5
bugtracker_url=http://bugs.centos.org/set_project.php?project_id=19&ref=http://bugs.centos.org/bug_report_page.php?category=yum
distroverpkg=centos-release
clean_requirements_on_remove=1

Save the changes and exit the file.

From now, every time you remove a packages, YUM goes through each package’s dependencies and remove them if they are no longer needed by any other package.

# yum autoremove

2: Using yum-plugin-remove-with-leaves Plugin

This extension removes any unused dependencies that were added in by an installation package, but would not be removed automatically. It also helps you to keep a system clean of unused libraries and packages.

First install this extension on your system using following yum command.

# yum install yum-plugin-remove-with-leaves

Once you have installed the extension, each time you want to remove a package, add the --remove-leavesflag, for example.

# yum remove policycoreutils-gui --remove-leaves

For more information, check out YUM’s man page:

# man yum

4 Ways to Lock Package Install or Updates Using Yum

Package Manager is software which allows a user in case of installation of new software, up-gradation of system, or updating any specific software and such sorts of things. In case of Linux based systems wherein one software has lots of dependencies which are required to be present on system for a complete installation of that software, such software’s like package manager become a much needed tool on every system.

Each Linux Distribution ships with its default package manager for above stated functionalities, but of all these most found ones are: yum on RHEL and Fedora systems (where it is being currently replaced with DNF from Fedora 22+ onwards) and apt from Debian.

If you’re looking for APT tool to block or disable certain specific package updates, then you should read this article.

Disable/Lock or Blacklist Certian Package Update Using APT

Dnf or Danified yum is replacing yum on Fedora systems which is another one in our list. If explored properly, these Package Managers can be used for following functionalities:

1. Installing new software from the repository.
2. Resolve dependencies of the software by installing those dependencies before installing the software.
3. Maintaining database of dependencies of each software.
4. Downgrade version of any existing software.
5. Upgrading the kernel version.
6. Listing packages available for installation.

We’ve already covered detailed articles separately on each individual package managers with practical examples, you should must read them to control and manager package management in your respective Linux distributions.

In the article, we will see how to lock/disable certain package updates using Yum package manager in RHEL/CentOS and Fedora systems (applicable till Fedora 21, later newer Fedora version ships with dnf as default package manager).

Disable/Lock Package Updates using Yum

Yellow dog Updater, Modified (yum) is package management tool in RedHat based distributions such as CentOS and Fedora. Various strategies used to Lock/Disable Package Updates using Yum are discussed below:

1. Permanently Disable Package for Install or Update

1. Open and edit the yum.conf file, which is located in /etc/yum.conf or in /etc/yum/yum.conf.

It looks like below:

[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=5
bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum
distroverpkg=centos-release
...

Here, to exclude certain package from installation or up-gradation, you just need to add exclude variable along with name of package you wish to exclude. For example, if I want to exclude all the python-3 packages from getting updated, then I will just append following line to yum.conf:

exclude=python-3*

For more than one package to exclude just separate their names by space.

exclude=httpd php 

[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=5
bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum
distroverpkg=centos-release
exclude=python-3*        [Exclude Single Package]
exclude=httpd php        [Exclude Multiple Packages]
...

Note: to include these packages, ignoring entries in yum.conf, use “-disableexcludes” and set it to all|main|repoid, where ‘main’ are those entered in yum.conf and ‘repoid’ are those whose exclusion is specified in repos.d directory, as explained later on.

Now let’s try to install or update the specified packages and see the yum command will disable them installing or updating.

# yum install httpd php
Loaded plugins: fastestmirror, langpacks, versionlock
Loading mirror speeds from cached hostfile
* base: mirror.nbrc.ac.in
* epel: mirror.wanxp.id
* extras: mirror.nbrc.ac.in
* updates: mirror.nbrc.ac.in
Nothing to do

# yum update httpd php
Loaded plugins: fastestmirror, langpacks, versionlock
Loading mirror speeds from cached hostfile
* base: mirror.nbrc.ac.in
* epel: mirror.wanxp.id
* extras: mirror.nbrc.ac.in
* updates: mirror.nbrc.ac.in
No packages marked for update

2. Temporarily Disable Package for Install or Update

2. Above was a permanent solution to exclude a package as unless file is edited, that package won’t get updated. Here is a temporary solution for this also. Just at the time when you go for any update, use -x switch in yum command to exclude package which you do not want to update, like:

# yum -x python-3 update

The above command will update all the packages whose updates are available, excluding python-3 on your system.

Here, for excluding multiple packages, use -x multiple times, or separate package names with ',' in a single switch.

# yum -x httpd -x php update
OR
# yum -x httpd,php update

3. Using --exclude switch works same as -x, just need to replace -x with –exclude and pass ',' separated list of package names to it.

# yum --exclude httpd,php

3. Disable Package Updates using Repository

4. For any package installed from any external source via adding a repository, there is another way to stop its up-gradation in future. This can be done by editing its .repo file which is created in /etc/yum/repos.d/ or /etc/yum.repos.d directory.

Add the exclude option with the package name in the repo. Like: to exclude any package say wine from epel repo, add the following line in epel.repo file:

[epel]
name=Extra Packages for Enterprise Linux 7 - $basearch
#baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
exclude=wine

Now try to update the wine package, you will get error like shown below:

# yum update wine
Loaded plugins: fastestmirror, langpacks, versionlock
epel/x86_64/metalink                                    | 5.6 kB     00:00     
Loading mirror speeds from cached hostfile
* base: mirror.nbrc.ac.in
* epel: mirror.wanxp.id
* extras: mirror.nbrc.ac.in
* updates: mirror.nbrc.ac.in
No Match for argument: wine
No package wine available.
No packages marked for update

4. Disable Package Update Using versionlock Option

5. Another way in yum to mask the version of any package thus making it unavailable for up-gradation, is to use versionlock option of yum, but to do this, you must yum-plugin-versionlock package installed on the system.

# yum -y install yum-versionlock

For example, to lock the version of package say httpd to 2.4.6 only, just write following command as root.

# yum versionlock add httpd

Sample Output

Loaded plugins: fastestmirror, langpacks, versionlock
Adding versionlock on: 0:httpd-2.4.6-40.el7.centos
versionlock added: 1

To view locked packages, use the following command will list the packages which have been version locked.

# yum versionlock list httpd

Sample Output

Loaded plugins: fastestmirror, langpacks, versionlock
0:httpd-2.4.6-40.el7.centos.*
versionlock list done

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