access permissions

The account is defined by the user name or login name and the password. The access permissions are generally set by the system administrator. The access permissions define to which user group the new user is assigned and the resulting permissions.


See access permissions.

ACL (Access Control List)

Extension of the conventional permission concept for files and directories.

ADSL (Asymmetric Digital Subscriber Line)

Transmission procedure that transmits data about one hundred times faster than ISDN in the telephone network.

AGP (Accelerated Graphics Port)

A high-speed slot for graphics cards based on PCI, but offering a larger bandwidth. Furthermore, AGP graphics cards can revert directly (without routing around the processor) to the random access memory and main memory, in contrast to PCI models, to swap graphics data there.

ATAPI (Advanced Technology Attachment Packet Interface)

ATAPI is a type of CD-ROM drive that is connected to an (E)IDE controller. Apart from ATAPI drives, there are SCSI CD-ROM drives, handled by a SCSI controller, and proprietary CD-ROM drives that use their own controller or are connected to a sound card.


A backup is a duplicate of data used to restore data that has been damaged or lost. Backups should be made regularly, especially of important files.


Maximum load capacity of a data channel.


Small component responsible for the initialization of important hardware processes. This essential procedure is complete when the boot menu appears on the screen.


A mostly personal collection of interesting web page or file references directly accessible in the browser.


The sequence of computer operations from power-up until the system is ready for use.


Program that searches and displays contents. Today it is mostly used for programs that display contents of world wide web pages.


A program or computer in a networking environment that connects to and requests information from a server.

command line

Text-based mode of operating in which commands are entered at a prompt. A command line can be accessed from within a graphical environment as well as from virtual consoles.


Formerly synonymous with terminal. In Linux, there are several virtual consoles that allow the screen to be used for several independent, parallel work sessions.

CPU (Central Processing Unit)

See processor.


The cursor is normally a block character that marks the place for input on a computer screen. This term also often refers to the symbol representing the location of the mouse in graphical interfaces.


A daemon (disk and execution monitor) is a program that monitors in the background and comes into action when required. Daemons answer FTP or HTTP requests, for example, or control activity in the PCMCIA slots.

DDC (Direct Display Channel)

Communication standard between the monitor and the graphics card, which transmits various parameters, such as monitor name or resolution, to the graphics card.


A structure for organizing files on a computer or network. A directory can contain a collection of files, other directories, or both. Organized in a hierarchical manner, many directories form a file system.

DNS (Domain Name System)

A system that converts name-based addresses to TCP/IP addresses and vice versa.


A program between the operating system and the hardware that translates the communication between these two layers.

e-mail (electronic mail)

The means of transporting mail electronically between registered users via a network. As with normal mail (often referred to as snail mail), the address must be entered. In e-mail, it is in the form sender@sender's-domain to recipient@recipient's-domain. E-mail not only lets you send text, but also sound files or pictures. It has many advantages: it is inexpensive and mail usually reaches its destination within minutes.

EIDE (Enhanced Integrated Drive Electronics)

Improved IDE standard that allows hard disks with a size over 512 MB.


A shell usually provides an environment in which the user can perform temporary settings. These settings include path specifications for programs, the user name, the current path, and the appearance of prompts. The data is saved in an environment variable. The assignment of the environment variables is possible, for example, by means of the configuration files of the shell.

environment variable

An element of the environment of the shell. Every environment variable has a name that is usually capitalized. The variables are assigned values, such as path names.


Popular standard for less expansive computer networks.

EXT2 (Second Extended File System)

One of the oldest file systems supported by Linux.

FAQ (Frequently Asked Questions)

Widely-used acronym for documents providing answers to frequently-asked questions.


Protects a local network or host from unauthorized access over a network using various security measures.

free software

See GNU.

FTP (File Transfer Protocol)

A protocol based on TCP/IP for transferring files.

GNOME (GNU Network Object Model Environment)

A user-friendly graphical desktop environment for Linux.

GNU (GNU is Not Unix)

GNU is a project of the Free Software Foundation (FSF)™. Closely linked to the GNU Project is the name of Richard Stallman (RMS). The aim of the GNU Project is to create a Unix-compatible operating system free not so much in the sense of free of cost, but in the sense of freedom: having the right to obtain, modify, and change the software. To guarantee the freedom of the source code (the actual program code), every change of the original code must be free as well, so modifications of or additions to the original software cannot compromise this freedom in any way. The now classic GNU Manifesto ( explains many aspects of this thinking. In legal terms, GNU software is protected by the GNU General Public License, or GPL (, and by the GNU Lesser General Public License, or LGPL (

In connection with the GNU Project, all Unix tools and utilities are being redeveloped and, in part, provided with more or enhanced functionalities. Even complex software systems, such as Emacs or glibc, are integral components of the project. The Linux kernel, subject to the GPL, profits from this project (especially from the tools), but should not be seen as the same thing.

GPL (GNU General Public License)

See GNU.

home directory

A private directory in the Linux system that belongs to a specific user (usually in /home/<username>). Except the superuser root, only the user has full access rights in his home directory.

host name

Name of a machine. In Linux, this is usually the name by which it can be reached on the network.

HTML (Hypertext Markup Language)

The most important language used in the World Wide Web for designing the contents. The layout commands made available by HTML define how a document looks and how it is displayed in a browser.

HTTP (Hypertext Transfer Protocol)

A protocol used between the browsers and Internet servers to transmit HTML pages over the World Wide Web.

IDE (Integrated Drive Electronics)

A widely-used hard disk standard in low-grade and middle-grade PCs.


Worldwide computer network based on TCP/IP, which is used by a very large population.

IP address

A numerical 32-bit Internet address, appearing in four decimal series separated by periods (for example,, which is uniquely assigned to a machine connected to TCP/IP networks.

IRQ (Interrupt Request)

A request to the operating system carried out by a hardware component or a program to assign it processor capacity.

ISDN (Integrated Services Digital Network)

A popular digital standard for high-speed data transferral over the telephone network.

KDE (K Desktop Environment)

User-friendly graphical desktop environment for Linux.


The kernel is the central core of the Linux operating system. It manages memory, contains the drivers that enable communication with the hardware, and handles processes and tasks. Applications run on top of the kernel.

LAN (Local Area Network)

A LAN is a local network and is usually rather small.

LILO (Linux Loader)

Small program installed in the boot sector of the hard disk that not only can start Linux, but other operating systems as well.


A link is a pointer to a file, just as widely used in the Internet as in the Linux file system. In Linux, there is a distinction made between hard and symbolic links. While hard links refer to the exact position in the file system, the symbolic link only points to the respective name.


High performance UNIX-like operating system core distributed freely under the GPL (GNU). The name is an acronym (Linus' uniX) and refers to its creator, Linus Torvalds. Although the name, in a strict sense, only refers to the kernel itself, the popular understanding of the term Linux usually entails the entire system.


Authentication of a user by user name and password to gain access to a computer system or network.


The procedure of closing down an interactive Linux session and getting back to the login prompt.

main memory

Physical memory of limited capacity that can be accessed rather quickly. This is often referred to as RAM, random access memory.

man pages

Traditional documentation for Unix systems, which can be read using the command man.

MBR (Master Boot Record)

The first physical sector of the hard disk from which the content is loaded to the main memory and executed by the BIOS. This code then loads either the operating system from a hard disk partition or a more sophisticated boot loader, such as LILO.


Algorithm for generating checksums.


This describes the insertion of file systems into the directory tree of the system.


Very efficient compression procedure for audio files that reduces the size by a factor of ten in contrast to an uncompressed audio file.


Operating systems that can invoke more than one program simultaneously are called multitasking systems.


Enables more than one user to work simultaneously on the same system.


The interconnection of several computers, accomplished normally using servers and clients.

NFS (Network File System)

A protocol for accessing a file system shared over a network.

NIS (Network Information Service)

A centralized data administration system in networks. User names and passwords can be simultaneously managed network-wide by NIS.

operating system

Program that permanently runs in the background on a computer and enables basic system operations.


Logically-independent section of a hard disk, each possibly containing different file systems. In Windows, also known as drives.


Unique description of a file's position in a file system.

plug and play

Automatic hardware component configuration technology. Resources, such as IRQ and DMA, are configured and managed separately from the system.


In Linux, started programs or executable files run as processes, often referred to as tasks. Processes can be controlled by commands like top entered in the shell.


The processor is the brain of every computer, working through and performing commands given by a user or a program in machine language. The processor has control over the entire system and is responsible for the actual performance of the computer.


See command line.


Standard specifically defined for regulating communication for hardware, software, or networks. There is a multitude of these standards. The most common examples are HTTP and FTP.


Most commonly used cache implemented by Internet providers that stores frequently requested contents in a database to allow other machines requesting those pages to load them directly from it. This process not only reduces the time it takes to download this information, but also conserves the available bandwidth.

RAM (Random Access Memory)

See main memory.


A file system that logs its changes to a journal. Compared to Ext2, this features allows a file system to be restored very speedily. ReiserFS is optimized for small files.


The user undertaking the configuration and maintenance of a complex computer system, such as a network. This system administrator is usually the only person who has access to all parts of the system (root permissions).

root directory

The base directory of the file system that does not have any parent directory (all other directories have a parent directory). In UNIX™, the root directory is represented as a /.

SCSI (Small Computer Systems Interface)

Hard disk standard implemented in servers and other high-level machines because of its high-speed performance. See server.


A server is usually a rather powerful computer that offers services, such as HTTP, DNS, and FTP, or data to other machines connected via a network. There are also programs called servers, like the X server.


An especially flexible command line often equipped with its own specific programming language. Examples of shells are Bash, sh, and tcsh.

SMTP (Simple Mail Transfer Protocol)

Protocol for transferring e-mails.

SSL (Secure Socket Layer)

Encryption procedure for transferring HTTP data.


See root.

system administrator

See root


See process.


Internet communication protocol finding increased use in local networks, known as intranets.


Telnet is the protocol and command for communicating with other hosts. Normally, the user only sees telnet as a means for logging into a remote system.


Formerly, the designation of a keyboard and monitor combination connected to a central computer. On workstations, this term is also used for programs that emulate a real terminal.


Name of the Linux penguin (see


UNIX is an operating system that is widely distributed, above all on workstations in networks. Since the beginning of the 1990s, there has been a freely available version for PCs: Linux.

URL (Uniform Resource Locator)

Unique Internet address that contains the type (e.g., http://) and the name of the host (e.g.,

user directory

See home directory.

VESA (Video Electronics Standard Association)

Industrial consortium that defines, among other things, important video standards.

wild card

Placeholder for one (symbol: ?) or more (symbol: *) unknown characters, most often used in commands (especially search commands).

window manager

A window manager is the layer that interacts between the X Window System and the user. It is responsible, among other things, for your desktop display. There is a wide variety of window managers available, one of the more popular ones being kwm for KDE.

WWW (World Wide Web)

Based on the HTTP protocol, this is a hyperlinked collection of documents, files, and images that can be viewed with a web browser.

X Window System

The X Window System is the standard for graphical interfaces in Linux. It is simply the middle layer between the hardware and the window manager, such as KDE or GNOME.


See X Window System.

YaST (Yet another Setup Tool)

The SUSE LINUX system assistant.


See NIS.