How to Add Memory, vCPU, Hard Disk to Linux KVM Virtual Machine

by Karthikeyan Sadhasivam on February 10, 2015

In our previous article of Linux KVM series, we explained how to Install Linux KVM and create a Guest VM.

But, once you’ve created a Guest VM, you need to know how to perform some of the routine maintenance activities on the VM.

This tutorial will explain how to perform the following Linux KVM VM activities:

  1. Add Memory to VM
  2. Add vCPU to VM
  3. Add Disk to VM
  4. Save VM Configuration
  5. Delete a VM


7 Steps to Build a RPM Package from Source on CentOS / RedHat

by Karthikeyan Sadhasivam on February 4, 2015

Sometimes you might have access to an open source application source code but might not have the RPM file to install it on your system.

In that situation, you can either compile the source code and install the application from source code, or build a RPM file from source code yourself, and use the RPM file to install the application.

There might also be a situation where you want to build a custom RPM package for the application that you developed.

This tutorial explains how to build a RPM package from the source code.

12 CUPS lpadmin Command Examples to Setup Printers on Linux

by Karthikeyan Sadhasivam on January 12, 2015

CUPS stands for Common UNIX Printing System.

lpadmin is a command line tool used to configure printer and class queues provided by CUPS.

A system running CUPS is a host that can accept print jobs from client computers, process them, and send them to the appropriate printer. It can also be used to set the server default printer or class.

This tutorial explains how to add a new printer, setup printer options, and manage printers on Linux environment using lpadmin command examples.

How Install and Configure OpenLDAP on CentOS / RHEL Linux

by Karthikeyan Sadhasivam on January 6, 2015

OpenLDAPLDAP stands for Lightweight Directory Access Protocol.

LDAP is a solution to access centrally stored information over network. This centrally stored information is organized in a directory that follows X.500 standard.

The information is stored and organized in a hierarchical manner and the advantage of this approach is that the information can be grouped into containers and clients can access these containers whenever needed.

The OpenLDAP hierarchy is almost similar to the DNS hierarchy.

This tutorial explains the process of building useful multi­-part commands piece by piece.

To build complex commands in the terminal, we need to understand piping. Piping is basically taking the output of one command and sending it to another command as input. This is done with the | (pipe) symbol.

Last month, a small project required me to repeatedly read similar XML files to provide test data for another program. I would have to do it so frequently that it would be annoying to have to download, save, parse and repeat. The basic requirements were:

logstash-logoLogstash is an open source central log file management application.

You can collect logs from multiple servers, multiple applications, parse those logs, and store it in a central place. Once it is stored, you can use a web GUI to search for logs, drill-down on the logs, and generate various reports.

This tutorial will explain the fundamentals of logstash and everything you need to know on how to install and configure logstash on your system.

7 Patch Command Examples to Apply Diff Patch Files in Linux

by Lakshmanan Ganapathy on December 2, 2014

When there is a security fix available for a particular software, we typically do a binary upgrade using the package management tools like yum or apt-get.

But, there might be situation where you have installed a software by compiling it from the source code.

In those situation, how do you apply the security fix to the software?

The answer is to download the security patch and apply it to the original source code and re-compile the software.

This tutorial explains how to create a patch file using diff, and apply it using patch command.

Yum ExcludeWhen you perform yum update, it will download the latest version of all the packages that are installed on your system, and upgrade them to the latest version.

You may be in situation where you might not want yum to automatically update one (or more) specific package.

In those situations, use the yum exclude option as shown in the examples below.