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Details
Redhat / CentOS
The Python 3 interpreter is not available on the RHEL 8 default installation. However, it can be installed with a single dnf command.

In this tutorial you will learn:
  • How to install Python 3 on Redhat 8.
  • How to to check Python version on Redhat 8.

Details
Redhat / CentOS
The following article will explain how to install and start SSH service on RHEL 8 / CentOS 8 system. SSH is a client-server service providing secure encrypted connections over the network connection.

In this tutorial you will learn:
  • How to Install SSH service.
  • How to start SSH service.
  • How to enable SSH to start after reboot.
  • How to open SSH port 22 for incoming traffic.

Details
Redhat / CentOS
By default the RedHat 8 Linux installation will start in the graphical mode. In case you encounter some issues you have an option to force the text mode TTY installation.

In this tutorial you will learn:
  • How to modify GRUB boot entry to force text mode installation.

Details
Redhat / CentOS
After installation of RHEL 8, Linux package repositories need to be enabled before you are able to install new packages. Any attempt to install new software will result with the following error message: 
This system has no repositories available through subscriptions.
OR 
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Updating Subscription Management repositories.
Unable to read consumer identity
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Error: There are no enabled repos.
OR 
This system is registered to Red Hat Subscription Management, but is not receiving updates. You can use subscription-manager to assign subscriptions.
No repositories available
In this tutorial you will learn:
  • How to Register your system to Red Hat Subscription Management.
  • How to Attach RHEL 8 subscription to your system.
  • How to Enable RHEL 8 Repository.
  • How to Disable RHEL 8 Repository.

Details
Redhat / CentOS
RHEL 8 / CentOS 8 comes by default, as it has been for many years already with a GNOME desktop environment. From this reason, in a broader sense when we talk about GNOME desktop installation we normally talk about RHEL 8 / CentOS 8 workstation.

In this tutorial we will be installing GNOME desktop as part of the workstation package group.

In this Install gnome on Redhat 8 tutorial you will learn:
  • How to install Gnome Desktop on RHEL 8 / CentOS 8.
  • How to change runlevel to boot to graphical interface in RHEL 8 / CentOS 8.

Details
Redhat / CentOS
The Nvidia CUDA toolkit is an extension of GPU parallel computing platform and programming model. The Nvidia CUDA installation consists of inclusion of the official Nvidia CUDA repository followed by the installation of relevant meta package.

Details
Redhat / CentOS
A hostname is the label or name linked to a device on a network. Its main purpose is to recognize a device on a specific network or over the internet. There are three different hostname types:
  • Static - Most of the time you will be interested in this type of hostname which is defined by user and the /etc/hostname configuration file.
  • Transient - This type of hostname is defined within kernel space and by default it is set to be the same as the static hostname. Transient hostnames can be set/updated by DHCP or mDNS at runtime.
  • Pretty - Pretty hostname allows for additional characters as per UTF8 character set hence serving rather only for presentation purposes. The pretty hostname also allows to include spaces.
This article will explain how to change or set hostname on RHEL 8 / CentOS 8 Linux server or workstation. To change hostname you will use the hostnamectl command.

In this tutorial you will learn:
  • How to change the static hostname.
  • How to change the transient hostname.
  • How to change the pretty hostname.
  • How to check the current hostname.

Details
Redhat / CentOS
The CentOS 7's support for Nvidia video graphic cards comes in a form of an open source nouveau driver. In case the nouveau driver is not a sufficient solution, users can install the official Nvidia driver as a proprietary alternative. This step by steps tutorial will guide you through the entire process on Nvidia driver installation.

To install Nvidia driver on other Linux distributions, follow our Nvidia Linux Driver guide.

Details
Redhat / CentOS

Objective

Our objective is to ensure that updating the operating system will run smoothly and without errors.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 6+

Requirements

Privileged access to the systems

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - given linux commands to be executed as a regular non-privileged user

Introduction

Keeping the system up to date is an every day task for a sysadmin, as well as a desktop user. By applying the latest (stable) available software on the system we can take advantage of the latest features, and will be more protected from security issues and hopefully suffer less from bugs. To update the system you will need configured yum repositories that act as the source of the updated software.

If you sit next to the machine that is running the operating system to be updated, you can easily act if something goes wrong during update, like checking the output on the terminal, or boot to a live system if the upgraded one does not return from reboot - but this is not always the case. Think of a datacenter with hundreds or thousands of (virtual) machines, or simply a physical PC that you have to upgrade remotely.

There are simple steps we can perform to prepare the system for upgrade, and possibly clear any problem that would endanger a successful update.

Details
Redhat / CentOS

Objective

Learn how to take advantage of the autofs daemon to automount devices and remote shares.

Requirements

  • Root privileges to install autofs package and edit configuration files

Difficulty

EASY

Introduction

Manually mounting and unmounting devices such as external USB drives or remote NFS or Samba shares can be tedious tasks to perform when administering a machine. The autofs daemon can help us automatically mounting a filesystem when needed and umounting it after a specified period of time. In this tutorial we will see the basic concept related to the automounter, and how to configure it.

Details
Redhat / CentOS

Objective

Our objective is to setup Apache httpd to work as a proxy in front of the Apache Tomcat application container.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5
  • Software: Apache httpd, Apache Tomcat

Requirements

Privileged access to the system

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - given linux commands to be executed as a regular non-privileged user

Introduction

Using Apache httpd as a proxy to an Apache Tomcat application container is a common setup. It comes with many use cases, the most trivial is serving static content from httpd, while providing services implementing heavy business logic from an application written in Java that resides in the Tomcat container.

Details
Redhat / CentOS

Objective

Our objective is to set up access to internal and remote yum repositories while some of them are behind proxy servers.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5

Requirements

Privileged access to the system

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - given linux commands to be executed as a regular non-privileged user

Introduction

In a corporate environment it is common to limit Internet access - both for security and accountability. This is often accomplished by using proxy servers that enable access to the Internet after some sort of authentication, while inspect and log all traffic passing trough them. This way the company can, for example find the employee who downloaded the virus that wreak havoc within the corporate system (or at least the employee who's credentials where stolen to do so), or filter the traffic, preventing access to well-known harmful sites to protect employee equipment.

Details
Redhat / CentOS

Objective

Our goal is to build rpm packages with custom content, unifying scripts across any number of systems, including versioning, deployment and undeployment.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5
  • Software: rpm-build 4.11.3+

Requirements

Privileged access to the system for install, normal access for build.

Difficulty

MEDIUM

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - given linux commands to be executed as a regular non-privileged user

Introduction

One of the core feature of any Linux system is that they are built for automation. If a task may need to be executed more than one time - even with some part of it changing on next run - a sysadmin is provided with countless tools to automate it, from simple shell scripts run by hand on demand (thus eliminating typo errors, or only save some keyboard hits) to complex scripted systems where tasks run from cron at a specified time, interacting with each other, working with the result of another script, maybe controlled by a central management system etc.

Details
Redhat / CentOS
If you have made a minimal CentoOS installation you can always install Graphical User interface as part of group packages. Let's first list all available package groups on the system: 
# yum group list
Loaded plugins: fastestmirror
There is no installed groups file.
Maybe run: yum groups mark convert (see man yum)
Loading mirror speeds from cached hostfile
 * base: centos.mirror.crucial.com.au
 * extras: centos.mirror.crucial.com.au
 * updates: centos.mirror.crucial.com.au
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
   Console Internet Tools
   Development Tools
   Graphical Administration Tools
   Legacy UNIX Compatibility
   Scientific Support
   Security Tools
   Smart Card Support
   System Administration Tools
   System Management
Done

Details
Redhat / CentOS

Objective

Our goal is to get used to the tools available to find out information about package dependencies on an RPM based system.

Operating System and Software Versions

  • Operating system: Red Hat Enterprise Linux 7.5
  • Software: rpm 4.11, yum 3.4.3

Requirements

Privileged access to the system.

Difficulty

EASY

Conventions

  • # - requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command
  • $ - given linux commands to be executed as a regular non-privileged user

Introduction

RPM, which stands for Red Hat Package Manager, is a well-known and mature package manager used by all Red Hat flavor distributions, as well as SuSE. With RPM the packager can define relations between packages, and even with versions of packages - for example, an Apache Tomcat server needs proper Java environment present to be able to run.

On the other hand, to install a Java environment, you don't need a Tomcat server - you may decide to run some different Java based application, maybe one written by yourself started by hand when needed to do it's job. In other words, the Tomcat server depends on Java.

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