Migrate WordPress multisite to new server

WordPress is a free and open source Content Management System written in PHP and is what a vast segment of websites is based on. The platforms has a vary nice feature: it allows the creation and management of multiple websites from the same installation. While migrating a WordPress installation is quite easy, to migrate WordPress multisite to a new server requires additional steps. In this tutorial we see how to proceed.

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How build grub from source on Linux

GRUB compile from source on Linux

GRUB is the acronym for GNU GRand Unified Bootloader: it is the bootloader used in practically all Linux distributions out there. Early in the boot stage, the bootloader is loaded by the machine firmware, either BIOS or UEFI (GRUB supports both of them), and it loads one of the available kernels. Being an essential software, grub is installed by default and available in the official repositories of distribution we are using;

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Introductory tutorial to Git on Linux

Git is without doubt the most used version control system in the world. The software is open source, released under the GPLv2 license, and was created by Linus Torvalds, which is also the father of Linux. In this tutorial we learn
the basic concepts behind its usage, we see how to create or clone a git repository and how to perform the basic actions involved in the git workflow.

In this tutorial you will learn:

  • The basic git concepts
  • How to create a git repository
  • How to clone a git repository
  • How to add file contents to the repository index
  • How to create a commit
  • How to push changes to a remote repository
  • How to pull changes from a remote repository
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Introductory tutorial to Git on Linux

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How to query packages information with the rpm package manager

RPM is the recursive acronym for RPM Package Manager: it is the default low level package manager in some of the most famous and most used Linux distributions, such as Fedora, Red Hat Enterprise Linux, CentOS, OpenSUSE and their derivatives. The software, as you can expect, is free and open source; when invoked with the -q option it can be used to query packages to retrieve specific information, such as dependencies, recommendations, files etc. In this tutorial we learn how to perform such queries.

In this tutorial you will learn:

  • How to run rpm in “query” mode
  • How to obtain general information about a package
  • How to read a package changelog
  • How to list the files provided by a package
  • How to list the scripts used by a package
  • How to list a package dependencies and recommendations
  • How to list packages rendered obsolete by an rpm
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How to query packages information with the rpm package manager

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How to work with dnf package groups

How to work with dnf package groups

Dnf is the default high-level package manager in the Red Hat family of distributions, which includes Fedora, Red Hat Enterprise Linux and all its clones. It is the successor of Yum, and indeed using the yum command in recent versions of the distributions mentioned above, is just another way to call dnf. Dnf has a lot of nice features
and plugins which help us install, update and remove software packaged in the “.rpm” format. In this tutorial we explore dnf package groups and learn how to handle them.

In this tutorial you will learn:

  • What is a package group
  • How to get information about a package group
  • How to list all available package groups
  • How to install, upgrade and remove a package group
How to work with dnf package groups

How to work with dnf package groups

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Ansible tutorial for beginners on Linux

A system administrator, in the vast majority of cases, has to take care of more than one server, so he often has to perform repetitive tasks on all of them. In these cases automation is a must. Ansible is an open source software owned by Red Hat; it is written in the Python programming lanaguage, and it is a provisioning and configuration management software which help us in the aforementioned cases. In this tutorial we will see how to install it and the basic concepts behind its usage.

In this tutorial you will learn:

  • How to install Ansible on the most used Linux distributions
  • How to configure Ansible
  • What is the Ansible inventory
  • What are the Ansible modules
  • How to run a module from the command line
  • How to create and run a playbook
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Introduction to Ranger file manager

Ranger is a free and open source file manager written in Python. It is designed to work from the command line and its keybindings are inspired by the Vim text editor. The application has a lot of features and, working together with other utilities, can display previews for a vast range of files. In this tutorial we learn how to use it, and explore some of its functionality.

In this tutorial you will learn:

  • How to install Ranger on the most used Linux distributions
  • How to launch Ranger and copy its configuration files locally
  • Ranger basic movements and keybindings
  • How to visualize hidden files
  • How to get preview of various types of documents
  • How to create, access and remove bookmarks
  • How to select files and perform actions on them
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How to take screenshots using maim on Linux

On Linux there are many utilities we can use to take screenshots. Every complete desktop environment, such as GNOME, KDE or XFCE has its integrated application specifically designed for this task, but many other small
desktop-independent programs exist. In this tutorial we talk about a very lightweight and versatile command-line application, maim (make image), and we see what are the many options we can use to modify its behavior.

In this tutorial you will learn:

  • How to install maim on the most used Linux distributions
  • How to take a screenshot of all the screen
  • How to save the screenshot in a specific format (png/jpg)
  • How to select a region of the screen interactively
  • How to take a screenshot of a window by passing its id to maim
  • How to take screenshots with a delay
  • How to use maim in a pipeline
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How to edit a system file with sudoedit preserving the invoking user environment

On Linux and other Unix-based operating systems, sudo is used to run a program with the privileges of another user, often root. When we need to modify a file which requires administrative privileges to be edited, if we launch our favourite text editor directly with sudo, it will run without the customization and settings we use when we invoke it normally, since the environment of the invoking user is not preserved. In this tutorial we will see how can we easily solve this problem and how we can modify system files securely by using sudoedit.

In this tutorial you will learn:

  • How to edit a system file using sudoedit
  • What are the steps performed when a file is edited with sudoedit
  • How to set the default editor used by sudo
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How to manage dynamic virtual hosts with Apache and the mod_vhost_alias module

The Apache web server has the ability to serve multiple websites from the same IP address, using virtual hosts. Each Virtual Host can be configured in the main server configuration file, or, thanks to the Include or the IncludeOptional
directives, in its own dedicated one. When the number of virtual hosts increases, their management starts to become troublesome. If their configuration is quite similar, we can manage them dynamically, thanks to the mod_vhost_alias module. In this tutorial we will see how to do it.

In this tutorial you will learn:

  • What is an Apache virtual host
  • How to check if the mod_vhost_alias module is enabled
  • How to load the mod_vhost_alias module on Debian and Red Hat family of distributions
  • How to manage dynamic virtual hosts using the mod_vhost_alias module
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How to change password and account expiry

How to change password and account expiry options on Linux using chage

Managing the period of time a password of a user should be valid and the date in which said account should expire are very important tasks a system administrator should be able to perform. While some of these parameter can be set when creating an account, it is also possible to change them at a second time, using the chage utility; in this tutorial we see how to use this utility.

In this tutorial you will learn:

  • How to get information about an user account ageing
  • How to set an account expiration date
  • How to set the minimum number of days which should pass between two password changes
  • How to set the password expiration date
  • How to set the inactive days threshold
  • How to set when a user should receive a warning about a future password expiration

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