Rhel

Red Hat Enterprise Linux (RHEL)¶

Red Hat Enterprise Linux

Red Hat Enterprise Linux (RHEL) is a Linux distribution developed by Red Hat and targeted toward the commercial market. Red Hat Enterprise Linux is released in server versions for x86-64, Power ISA, ARM64, and IBM Z, and a desktop version for x86-64. All of the Red Hat's official support and training, together with the Red Hat Certification Program, focuses on the Red Hat Enterprise Linux platform. Red Hat Enterprise Linux is often abbreviated to RHEL, although this is not an official designation.

What versions of RHEL are available?¶

Current Version	Supported Until
RHEL 8	May 31, 2029
RHEL 9	May 31, 2032

Using RHEL¶

If you are familiar with CentOS, you should have no trouble using RHEL. If you are not familiar with CentOS, this guide will help you get started with some of the basics.

Installing Software & Updates¶

yum and dnf

RHEL 7 uses the yum package manager, while RHEL 8 and 9 use the dnf package manager. However, yum is still available on RHEL 8 and 9 for backwards compatibility but is deprecated and will probably be removed in a future release.

RHEL uses the yum package manager to install software and updates. You can install software using the yum install command. For example, to install the Apache web server, you would run the following command:

yum install httpd

You can also install multiple packages at once by separating them with a space. For example, to install Apache and PHP, you would run the following command:

yum install httpd php

To update your system, you can use the yum update command. For example, to update all packages on your system, you would run the following command:

yum update

Managing Services¶

RHEL uses systemd to manage services. You can start, stop, restart, and check the status of services using the systemctl command. For example, to start the Apache web server, you would run the following command:

systemctl start httpd

Note

You must run the systemctl command as root or with sudo.

Note

The systemctl command does not provide any output if the command is successful. If the command fails, it will provide an error message.

Note

Service names may vary based on the distribution. For example, the Apache web server is named httpd on RHEL, but it is named apache2 on Ubuntu.

To stop the Apache web server, you would run the following command:

systemctl stop httpd

To restart the Apache web server, you would run the following command:

systemctl restart httpd

How to register subscription¶

NodeSpace offers RHEL as part of the "BYOL" (Bring Your Own License) program. To register your new RHEL system and attach it to your subscription, run the following command:

subscription-manager register

Provide your Red Hat login and the system will let you know when it is successfully registered.

Unable to run yum update¶

If you are unable to run yum update and receive the following error:

[root@rhel-test ~]# yum update
Loaded plugins: product-id, search-disabled-repos, subscription-manager

This system is not registered with an entitlement server. You can use subscription-manager to register.

There are no enabled repos.
 Run "yum repolist all" to see the repos you have.
 To enable Red Hat Subscription Management repositories:
     subscription-manager repos --enable <repo>
 To enable custom repositories:
     yum-config-manager --enable <repo>

You will need to register your system with Red Hat. See the section above for instructions on how to register your system.

How to version lock a package¶

Lock a package to a specific version only, and no later
Exclude a package from yum update
What is yum versionlock?

Install the appropriate package based on your version of RHEL:

For RHEL 6 and 7:

yum install yum-plugin-versionlock

For RHEL 8 and 9:

dnf install python3-dnf-plugin-versionlock

The /etc/yum/pluginconf.d/versionlock.list will be created on the system.

To lock a package to a specific version, run the following command:

yum versionlock <package>

For example, to lock the httpd package to version 2.4.6-97.el7, you would run the following command:

yum versionlock httpd-2.4.6-97.el7

The plugin stores a package list in /etc/yum/pluginconf.d/versionlock.list, which you can edit directly. yum or dnf will normally attempt to update all packages, but the plugin will exclude the packages listed in the versionlock.list file.

The above configuration will not allow yum update or yum upgrade to update any of the httpd packages to version greater than what was installed at the time the locking was performed.

See the yum-versionlock(1) for a list of all available commands.

To remove a package from the version lock list, run the following command:

yum versionlock delete <package>

Or to remove all packages from the version lock list, run the following command:

yum versionlock clear