What to look for

Apache
The world’s favourite Web server, Apache is included as a standard component in most Linux distributions. However, it’s not the only Web server available for the Linux platform with others such as Zeus Web Server (ZWS) also available.

Beowulf
Beowulf refers to a clustering technology used to link Linux computers together to provide the processing power required for demanding high-performance computing (HPC) applications. Note that other clustering solutions are also available.

CUPS
A modern replacement for the Berkley Line Printer Demon (LPD), the Common Unix Printing System (CUPS) is free software, published under the GNU General Public License, that allows Linux applications to print to network printers using the Internet Printing Protocol (IPP). Clients use a common PostScript driver with documents converted to the native print language, if required, by the CUPS server.

GNOME
Short for GNU Network Object Modelling Environment, GNOME is a Linux graphical desktop built on top of X Windows. Unlike Microsoft Windows there are several Linux desktops to choose from, with GNOME the default on Red Hat and Debian distributions while others such as SUSE (Novell) favour KDE.

GNU/GPL
A kind of in-joke, GNU is shorthand for 'GNU’s not Unix', and effectively describes the ethos of the Free Software Foundation, the main sponsor of the GNU Project. Tangibles from the GNU Project include software tools and a range of licences including the GNU General Public License (GPL), which is widely employed to make open source software available for free.

Journaled file system
A common Linux option, a journaled file system (JFS) maintains a log, or journal, of all disk activity so that lost files and data can be recreated in the event of a hardware or software failure. A journaled file system can also recover data not yet written to disk at the time of the system crash or hardware failure.

KDE
Short for the K Desktop Environment, KDE is a Linux graphical desktop built on top of X Windows. It’s the default desktop on SUSE Linux (from Novell), while others such as Red Hat, Ubuntu and Debian favour the rival GNOME solution.

Kernel
The core software on which any Linux implementation is based, and a common component regardless of the vendor/developer involved. Kernel version numbers have three parts (e.g. 2.4.1), the major release level being indicated by the first number, followed by the minor version number (which will be even for a stable production release and odd for a development version). Any additional numbers indicate patch or update releases.

LiLo
Short for 'Linux Loader', this small program is the first to start when the host computer is booted and then loads Linux according to a preset configuration. It also allows other operating systems, such as Windows, to be booted instead. Some implementations of Linux use LiLo, others use alternatives such as Grub.

Linux distributions
Often referred to as 'distros', Linux distributions are complete implementations of the Linux OS from specific developers such as Red Hat, SUSE (Novell), Debian, Mandriva, Ubuntu, Slackware and so on. Each distribution is typically available either as a Web download or on CD/DVD-ROM, can be installed on a variety of industry standard hardware and, in addition to the Linux kernel, will include varying amounts of optional application software.

MySQL
An open source SQL database server bundled with most Linux distributions, MySQL is used to provide the database back-end for a wide range of applications.

NFS
Short for Network File System, NFS is a protocol that allows files to be shared across a network. Originally developed by Sun for use on its Unix operating system, NFS is widely used on both Linux and Unix platforms. Server volumes are 'published' on the network and can then be 'mounted' by remote hosts and accessed as though locally attached. NFS is different to and incompatible with the SMB/CIFS protocol used on Windows networks.

Open Source
Software where the source code is made freely available for anyone to see, modify and use. Under most open source licences, such as the General Public Licence (GPL), any modifications must also be made available and freely distributed with the executable code involved. However, open source software isn’t always free as developers can charge for the code they sell and may include proprietary components of their own.

Partitioning
Rather than treat a hard disk as a single contiguous storage area, it's commonplace to divide it into two or more logical partitions. Each partition can then be treated as though it were a separate disk, optionally formatted with a different file system and able to boot a completely independent operating system. Most Linux implementations use multiple partitions to ensure that corruption in one doesn’t affect other parts of the OS.

PostgreSQL
PostgreSQL is a popular open source SQL database server for Linux.

Root
Also referred to as the 'superuser' or just 'su', the root user on a Linux system has full access rights to the OS, installed applications and files. The root/su account should only be used for management operations that require these elevated permissions.

RPM
Short for 'Red Hat Package Manager', RPM allows Linux patches, updates and applications to be installed or uninstalled without the need for in-depth technical knowledge. Software is packaged as a single file containing all the dependency, setup and other information required. Originally developed by Red Hat, RPM is now widely employed on other Linux distributions.

Samba
Samba is a utility that enables a Linux server to share files using the same SMB (Server message Block) protocol used by Microsoft Windows, also referred to as CIFS (Common Internet File System). Linux-hosted Samba servers can be used to share both files and printers on Windows network and, in the latest version of the software, can also act as Domain servers in Active Directory setups.

Shells and shell scripts
A shell is a program that provides a command line interface through which users can interact with a Linux/Unix operating system. Interaction is via built-in commands and executable utilities which can be further automated using scripted procedures known as shell scripts.

Tux
Tux is the Penguin created by Larry Ewing and chosen by the creator of Linux, Linus Torvalds, as the official Linux logo.

X Windows
X Windows is the software that enables Linux to interact with users via a graphical user interface (GUI) rather than a simple command line. There are several different implementations, one of the most popular being XFree86, and several different Linux desktops, including GNOME and KDE, are written to run on the X Windows platform.