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If grep is one of your favorite tools, chances are that you will like ack even better. ask a Perl-based command-line utility similar to grep, but designed to improve the search speed and capabilities of grep. Especially if you are a programmer, I strongly recommend replacing grep with ack. The usage of ack is heavily optimized for code search, so a programmer can perform complex search on source code trees with fewer keystrokes.

SSL (Secure Sockets Layer) and its descendant TLS (Transport Layer Security) are the most widely used protocols for encrypting data that is exchanged between a server and a client. These protocols often use X.509 certificates and asymmetric cryptography. In this tutorial, we demonstrate how to add security to a mail server through TLS/SSL-based encryption.

In today's multi-tenant data centers, virtualization technology is being extended from traditional hypervisor-based server virtualization to network virtualization.In this environment, software-based virtual switches are commonly deployed on servers along with hypervisor, bridging traffic among different virtual machines (VMs). In this tutorial, I am going to demonstrate how to install and configure KVM and Open vSwitch (OVS) on Ubuntu or Debian.

This tutorial will discuss how to set up a working mail server in Ubuntu or Debian. As we know, the two major protocols used in a mail server are SMTP and POP/IMAP. In this tutorial, postfix will be used for SMTP, while dovecot will be used for POP/IMAP. Both are open source, stable and highly customizable.

If you are trying to check Internet speed from a remote headless server, VPS or an otherwise desktop-less system, Speedtest.net's Flash-based user-friendly interface would be no good. For those of you, there is a command-line interface (CLI) version of Speedtest.net, known as speedtest-cli. Here I will demonstrate how to use speedtest-cli to check Internet speed from the command line in Linux.

If you know what you are doing on Facebook, you can consider a much lightweight alternative Facebook client called fbcmd, a command-line client for Facebook, instead of heavy-weight Facebook web access. Using fbcmd's command line interface (CLI), you can do pretty much everything you would do on Facebook, but without having to download superfluous dynamic content. This tutorial covers how to access Facebook from the command line on Linux, by using fbcmd CLI.

Email service is one of the most often used services globally. Today almost everyone has at least one email account. Although clicking on the email send button and delivery of an email message appear seamless, a lot of events take place behind the scenes to make sure that the email reaches its final destination. This tutorial goes over how the delivery of an email message actually takes place in reality.

KDE desktop has long been favored by many Linux geeks because it has every element to fulfill their appetite: customizable every bit of it, aesthetically pleasing desktop effects, openness to adopting new technologies such as semantic desktop, etc. Beyond all these bells and whistles, the KDE desktop community constantly tries to advance the state of the art of the desktop, experimenting with wild new ideas. One such effort is so-called KDE Connect, which is a brainchild of Albert Vaca, as part of his Google Summer of Code 2013. The objective of KDE Connect is to seamlessly connect all sorts of devices to KDE desktop, so they can talk to each other.

The most well-known tool to minify CSS and JavaScript is YUI Compressor, which is part of YUI (Yahoo! User Interface) JavaScript library written by Yahoo! developers. In this tutorial, I will describe how to compress CSS or JavaScript from the command line on Linux by using YUI Compressor.

Currently, three versions of SNMP are available: v1, v2c and v3. SNMPv3 adds some additional features, including authentication and encryption schemes (e.g., MD5, SHA, AES and DES). This makes SNMPv3 more secure and advisable while you run SNMP queries over the Internet. This tutorial describes how to configure SNMPv3 in Ubuntu, CentOS and Cisco hardware.

User account management is one of the most critical jobs of system admins. In particular, password security should be considered the top concern for any secure Linux system. In this tutorial, I will describe how to set password policy on Linux. I assume that you are using PAM (Pluggable Authentication Modules) on your Linux system, which is the case on all recent Linux distros.

Looking Glass (LG) is a web-based tool that helps network operators analyze how traffic is routed to and from a particular AS's network. This tutorial will describe how to set up a BGP Looking Glass server on CentOS.

Zeal is an offline API documentation browser. The idea of Zeal comes from Dash, MacOS X documentation browser, which comes with 130+ curated document sets (docsets) of popular programming languages, scripts, and frameworks. Zeal can access the same docsets contributed by Dash. Each docset contains detailed API definition, code snippets, and user-contributed notes. This tutorial describes how set up Zeal to browse and search API documentation offline on Linux platforms.

AppArmor, which is considered an alternative to SELinux, is the default application access control system of Ubuntu. Many Ubuntu packages (e.g., libvirt, MySQL) come with their corresponding AppArmor profiles which restrict the capabilities of programs to be installed. If you are suspecting that AppArmor is interfering with particular software, you can try disabling its AppArmor profile as part of troubleshooting. Here is how to disable a particular AppArmor profile.

One of routine tasks for system admins is to update installed programs with the latest patches and hotfixes, as well as upgrade software to a more recent release with new bells and whistles. The latest MySQL 5.6 was released early this year, targeting better performance and scalability. For those of you wanting to try out the latest bleeding edge MySQL, this tutorial describes how to upgrade MySQL server on Debian or Ubuntu.

Nagios comes with a wide range of built-in scripts for monitoring services. This tutorial will cover the process of using some of these scripts for checking common services, such as MySQL, Apache web server, DNS, etc.

Once you have a fully working Raspberry Pi system, it may not be convenient for you to continue to access Raspberry Pi directly via a keyboard and HDMI/TV cable connector dedicated to Raspberry Pi. Instead, you will want to remote control "headless" Raspberry Pi from another computer. This tutorial will show you how to remote control your Raspberry Pi.

There is no shortage of Twitter clients available, differing in terms of features, operating system support, interface, mobile capabilities, etc. If you are one of those command line junkies, there is one for you as well. This tutorial will demonstrates how to access Twitter from the command line using Twitter CLI. Installation and basic usage examples will be covered.

This tutorial describes how to configure DNS servers statically on CentOS or Fedora in case you want to use public DNS servers (e.g., Google DNS), not those assigned by a DHCP server.

While some of you may dismiss Chromebook as an incapable bare-bone laptop, the matter of fact is that sales of Chromebooks continue to soar while the rest of PC sales are plummeting. If you want to try out Google's Chrome OS powered Chromebook without purchasing Chromebook hardware, you can actually test-run Chromium OS as a virtual machine (VM). In this tutorial, I will explain how to install and run Chromium OS on VMware Player.