DNF system upgrade is recommended upgrade method for Fedora 21 and later releases. DNF is a kind of successor for FedUp (FEDora UPgrader), which is now obsolete, not supported any more by Fedora Project and should not be used any longer.
In this article we upgrade from Fedora release 22 (Twenty Two) to Fedora release 23 (Twenty Three) or higher release in few simple steps, using DNF system upgrade method.
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Linux installation process can be simplified by means of Kickstart Installation method, used in Linux distributions like: Red Hat, Debian, Fedora, CentOS, Ubuntu. This method utilizes so called Kickstart File, which describes the configuration, required setup and post installation tasks for Kickstart Linux installation.
Kickstart File can be placed in the remote repository, accesible via NFS, HTTP, FTP, etc…, or can be included in ISO image, which is pretty convenient, especially when we don’t want to or don’t have a possibility to create network repository to store a Kickstart File.
In this tutorial we will download original CentOS 7.2 / RHEL 7.2 ISO image, mount it in the Linux file system, modify it by adding Kickstart File (ks.cfg) and re-pack it to create custom UEFI bootable RHEL 7.2 ISO image using mkisofs command.
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Have you ever tried to quickly create USB Boot Disk in Linux and had no dedicated software to create one?
For a long time Linux distributions have come with basic tools like dd utility out of the box. dd command can be used to quickly create USB Boot Disk from the given ISO file without using dedicated tools like unetbootin.
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The sudo command offers a mechanism for providing trusted users with administrative access to a system without sharing the password of the root user.
A sudoer (regular user added to sudoers) once authenticated, can execute the administrative commands like they were run by the root user.
In this tutorial we present two examples:
Have you ever wondered how to find RPM package which contains particular script, application or command in your RedHat / CentOS or any other Yum / RPM based operating system? Have you ever needed to find the RPM package which provides some service or feature?
Yum package manager provides parameters to fast and easy search for particular files / features in Red Hat / CentOS RPM repositories:
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Kdump is a reliable Kernel Crash Dumping Mechanism, in which a crash dump is captured by a second kernel (crash kernel) booted when the main kernel crashes.
This second kernel (crash kernel) uses a small amount of memory for booting and capturing the dump image (vmcore) file. The part of memory reserved by the main kernel is used by the second kernel to boot. Preserving the main kernel’s crash dump is a result of kexec mechanism which allows to boot the second kernel without the necessity of rebooting the system and passing through BIOS procedures.
The time for capturing the vmcore file depends on the amount of the occupied memory during crash. The average time of capturing a 5GB vmcore file is approximately 20-25 minutes.
When the kdump is successfully made during the system crash, a vmcore file is created in a dump location (usually /var/crash/ directory) and next the system reboots. After crash the vmcore file should be analyzed to determine root cause of the failure.
Below we present how to configure and manage kdump service on CentOS 7 / RHEL 7.
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Puppet is an open-source configuration management tool written in Ruby by Luke Kanies which includes its own declarative language to describe system configuration.
In this tutorial we install and configure Puppet on CentOS 7 based hosts.
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Xfce is a free and open-source desktop environment for Unix and Unix-like platforms which aims to be fast, intuitive, user-friendly and lightweight, while still being visually attractive for user.
In the below short tutorial we will install Xfce 4 Desktop Environment on CentOS 7 system in few steps.
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KVM (Kernel-based Virtual Machine) is a virtualization infrastructure for the Linux which requires a processor with hardware virtualization extension to be able to host guest sytems. KVM is convenient solution to test and try different operating systems if you don’t have a possibility to purchase expensive and power consuming physical hardware.
The below tutorial presents KVM (QEMU) installation and setup along with Linux Bridge configuration on CentOS7 / RedHat7 operating system.
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Elasticsearch is a search server/engine based on Apache Lucene. It provides a multi-node distributed full-text search engine with an HTTP web interface and sophisticated RESTful API. Elasticsearch is developed in Java and is released as open source under the terms of the Apache License.
There are several types of nodes in Elasticsearch architecture:
In this tutorial we will install Elasticsearch Cluster on three Centos 7 based nodes: Master-eligible node, Data node and Client node.
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