# Glossary

# A

Applet

  An application working inside a small window in a panel.

Application launcher

  A button in the panel which launches an application or executes a command when pressed.

ASCII

  American Standard Code for Information Interchange; the standard describing a collection of characters and codes (i.e. sequences of zeros and ones, or numbers) assigned to them. ASCII characters include Latin letters, common punctuation marks, some special symbols usually found on the keyboard such as & and $, and some control symbols, such as the codes used for denoting end of line and end of file; it does not include accented symbols. The corresponding codes run from 0 to 127.

  When you see a mention of an "ASCII file" or "ASCII text" somewhere, it usually means a plain text file which only uses symbols defined in ASCII standard, with no formatting information such as fonts to be used.

  ASCII is defined as a standard of American National Standards Institute (ANSI); the offical reference is "ANSI X3.4-1986". You can find a reproduction of it in many places on the Internet, for example, on CNET Web page.

  See Also: Encoding.

Attachment

  Any file accompanying an e-mail message in a special format so that it can be viewed or saved to disk independently of the main message body.

# B

Background

  To make a program run without any visible output; to put a program which is already running into the background.

  On the UNIX command line, the character `&` appended to a command will make that command run in the background.

  See Also: Foreground.

Binary

  An executable program, so called because the file containing the program consists of machine-readable binary digits, i.e. ones and zeroes.

Bit

  The minimal possible unit of information, a digit which can take values 0 or 1. Saying that the file has length n bits is equivalent to saying that it can be written as a sequence of n zeros and ones.

Byte

  8 bits, i.e. a sequence of 8 zeros and ones.There are 256 possible such sequences, so one can also say that one byte represents a number ranging from 0 to 255.

  Byte is the basic building block of filesystem: all files are composed of bytes. For text files, each byte represents one symbol (see definition of encoding for more information).

# C

Cache

  A short-term storage area in RAM or on the hard disk. Many programs use caches to store recently-accessed files or other items.

Character set (charset)

  A collection of symbols, such as letters of one or several alphabets, digits, punctuation marks, etc. Commonly used together with encoding.

Clipboard

  The temporary buffer into which text or other data can be copied, to be used later by pasting into a different location. Most applications support the clipboard either through native mouse-based cut and paste functionality of X Window System, or through specialised menus and other interfaces.

Command line options

  Parameters or arguments given on the UNIX command line after a program name, which tell the program how to run. For instance, in the command `ls -l` the `-l` is a command line option telling the ls program to produce a "long" listing.

Cursor

  A highlighted or animated icon which indicates the current position of the mouse on the screen, or the position where keyboard input will occur in a text window.

# D

Daemon

  A background process providing basic system or network services.

Desktop

  The visible screen area, on which windows, icons, and other graphical items may be placed.

  See Also: Virtual desktop.

Desktop environment

  Software which provides graphical user interface for users desktop. In addtition to capabilities provided by a window manager (that is, ability to move, resize, and hide windows), a desktop environment usually also includes such elements of GUI as a File Manager with drag-and-drop capabilities, Panel used for keeping your favorite applications and applets, and a set of other utilities. Most popular desktop environments for UNIX include GNOME, KDE and CDE (soon to be replaced by GNOME).

Device

  A piece of hardware with which the system interacts, such as a hard disk, modem, or mouse.

Directory

  A branch within UNIX's hierarchical file system; a "folder" containing files or other directories (called "subdirectories").

  See Also: Filesystem.

DNS

  Domain Name Service; converting domain names (such as www.gnome.org) into IP addresses such as 209.116.70.70. If you want to use domain names, your computer must be configured to connect to one of DNS servers which would do this conversion.

# E

Electronic mail (e-mail)

  A way of exchanging messages between users of computers connected to a network (local or Internet).

Encoding

  A correspondence between characters of some character set and character codes, i.e. internal computer presentation of the symbols. In order to be able to read a text file, you need to know its character set and encoding.

  In most encodings, each symbol is represented by one byte, which is equivalent to a number from 0 to 255; the characters corresponding to codes 0 to 127 coincide with the ASCII standard, while the characters with codes higher than 127 vary between encodings. For Chinese, Japanese, Korean, and similar character sets, each symbol is represented by 2 bytes.

  The most common encoding is iso-8859-1; in addition to ASCII characters, it also contains accented letters covering most of Western European languages.

Environment variable

  A global "setting", or configuration parameter, which is available to all applications. Each environment variable has a name and a value (which usually is a string of symbols or an integer number). Any application you run can access any of the environment variables. For example, there is a standard environment variable `HOME`, whose value is the user's home directory (for example, `/home/joe`), and any application which wants to create a file in your home directory uses this variable to find out what your home directory is.

  To view all currenlty defined environment variables, use the command printenv (provided that you have GNU shell utils package installed). To modify a value of environment variable, use the command export `NAME`= `VALUE`; if you are using bash shell or setenv `NAME VALUE`; if you are using csh or tcsh shell.

Ethernet

  A protocol for network communication, developed in the 1980s and commonly used for Local Area Networks (LANs) and other network communication.

# F

File

  Any piece of information (text, graphics, executable) put together and given a name. All the information you have on the hard drive is arranged as a collection of files.

  See Also: Filesystem.

Filesystem

  A collection of all the files and directories on a system arranged in a tree-like hierarchy.

  See Also: File, Directory.

Foreground

  To run a program so that its output is visible to the user, or to bring a previously "backgrounded" program to the foreground. Programs running in the foreground can display output and receive input from the user.

  See Also: Background.

File Transfer Protocol (FTP)

  A protocol for exchanging files over the Internet or local network. There is a number of utilities based on this protocol, such as `gFTP`; you can also use command ftp on the command line. In addition, most file managers and Web browsers have built-in FTP capabilities.

Free software

  As defined by Free Software Foundation, free software is software that comes with permission for anyone to use, copy, and distribute, either verbatim or with modifications, either gratis or for a fee. In particular, this means that the source code must be available.

  This is very close, but not identical, to the notion of Open Source software. Detailed discussion of this and related topics can be found on Free Software Foundation's Web page.

  See Also: GNU General Public License (GPL).

# G

GNOME

  A free desktop environment for UNIX and UNIX-like operating systems; one of the two leading desktop environments for Linux (the other one is KDE). For more information, please visit GNOME Web site.

  Officially, GNOME stands for GNU Network Object Model Environment. The only part of this name that really matters is GNU, which is there to indicate that GNOME is a part of the larger GNU project.

GNU

  GNU's Not UNIX; a project to develop a complete UNIX-like operating system which is free software. Combination of tools and utilities produced by GNU project with Linux kernel is widely known under the name "Linux operating system"; more accurately, such a system should be called GNU/Linux.

  For more information about GNU project, visit its Web page.

GNU General Public License (GPL)

  A software license developed by the Free Software Foundation. In short, it allows anyone to use, copy, distribute, or sell the software, in original or modified form, as long as you distribute the program's source code along with the binaries, and you distribute them again under the GPL. A copy of the GPL is included as an appendix to GNOME User's guide. You can also view GPL on-line on FSF's Web page.

  GPL plays an extremely important role in the free software movement; almost all of GNU project software, as well as Linux kernel, is distributed under GPL. For a detailed discussion of history, ideas and philosophy related to GPL and free sofware in general, visit FSF's Web page.

  See Also: Free software, Open Source, GNU.

GIMP Toolkit (GTK)

  A collection of tools for creating screen widgets such as scrollbars, menus, checkbuttons, etc. in applications. GTK is used by all GNOME applications.

# H

Hot Key

  Hot-keys are keyboard combinations used to do actions on a computer instead of using the mouse to do the same action. Hot-keys can speed up computer usage. Also known under the name "keyboard shortcut" or "keyboard accelerator".

HTML

  Hypertext Markup Language; the language in which all the Web pages in the world are written. HTML can also be used for e-mails, which allows having nicely formatted e-mails, possibly including images and links.

  More information about HTML can be found on the Web page of World Wide Web Consortium, which is the official maintainer of HTML standard.

HTTP

  Hypertext Transfer Protocol; the protocol by which web pages and other web-accessible resources are delivered. Whenever you are browsing the Web, your browser uses HTTP to communicate with the Web server and request a Web page.

  HTTP is defined in RFC 1945 (HTTP 1.0) and RFC 2068 (HTTP 1.1).

# I

IDE

  Intergrated Drive Electronics; an interface for connecting hard drives and other similar devices to your computer. IDE is an old interface; nowadays, most drives use an enhanced version of IDE, EIDE.

  See Also: SCSI.

Icon

  A small picture used within a graphical user interface to indicate a program, file, or other part of a computer system.

Internet

  Unless you spent the last 20 years on a deserted island, you probably know what Internet is. But just in case: Internet is the network of millions of computers all around the world, connected to each other by some hardware means (cables, wires, phone lines, communication satellites) and communicating with each other using some standard protocols. Internet makes it possible for users of these computers to send and receive electronic mail, browse the World Wide Web, exchange files (using FTP protocol), remotely login into your computer from other places (using telnet), and more.

IP address

  A unique address assigned to each computer connected to the Internet or a local network. Has the form a.b.c.d, where a,b,c,d are numbers from 0 to 255, subject to a number of rules and conventions.

  All communication between computers on the Internet is based on IP addresses; however, on a properly set up network you can instead use domain names (such as www.gnome.org), which are automatically transformed to IP addresses using Domain Name Service (DNS).

# K

KDE

  A desktop environment for UNIX and UNIX-like operating systems; one of two leading desktop environments for Linux (the other one is GNOME). For more infrmation visit KDE Web site.

Kernel

  The core component of an operating system, responsible for basic operations such as accessing the files, input/output, managing the processor and memory resources, etc. All other tools, utilities, and applications use the kernel.

# L

Linux

  A free (as in GNU GPL) UNIX-like operating system, written in collaboration by hundreds of developers all around the world, most of them volunteers. One of the most successful and famous free software projects.

  Strictly speaking, the name "Linux" only applies to the kernel of the operating system. Most of other tools and utilities necessary for system functioning came from GNU project, so the operating system should be properly called "GNU/Linux"; however, for convenience reasons most people use the name Linux for the whole operating system.

  There is a tremendous amount of information about Linux available on the Internet; good starting points are www.linux.com, www.linux.org. There is also a number of good books about Linux available in bookstores; if you have a Linux system, you probably also have a lot of Linux documentaion installed on your system.

login

  The process by which a user authenticates herself to a computer system, usually by typing in a username and password.

  See Also: User, Username, Password.

# M

Mail Client

  An application which a user reads and sends their e-mail with. Also called Mail User Agent (MUA).

Manual page (manpage)

  A documentation resource commonly provided with UNIX programs. Manual pages typically contain concise technical listings of available command line options and other settings which affect the running of the program. Can be viewed using GNOME Help Browser or by typing man `commandname` on the command line.

Menu

  A list of possible actions or options available within a program.

MIME type

  A "type" of the file, describing what kind of data and in which format this file contains; for example, MIME type `image/jpeg` is used for graphic files in JPEG format. Used by many applications (such as file manager) to determine what application should be used to open or edit a given file. This can be configured using `GNOME Control Center`.

  The acronym MIME stands for Multipurpose Internet Mail Extension, since originally it was used to describe types of files sent in e-mail.

Mount

  A command instructing the operating system to incorporate contents of a device (such as a hard drive or a CD-ROM) into the system's link file system. Requires the device name (e.g. `/dev/cdrom`) and the mount point, i.e. the name of the directory under which the contents of the device will be shown (e.g., `/mnt/cdrom`). You must mount any device before you can access files on it, and unmount it before physically disconnnecting or removing the drive. For more information, see Appendix If you are new to UNIX in GNOME User's Guide or manual page for mount.

Mount point

  See: Mount

Mouse cursor

  An small icon (usually an arrow) used to indicate the position of the mouse on the desktop.

# N

Nautilus

  `Nautilus` is the next generation file manager for GNOME being written by Eazel.

# O

Open Source

  Refers to software for which both the executable files and the source code can be freely redistributed and re-used in other products. This term was introduced by Open Source Intiative; it is very close, but not identical to the notion of free software used by the Free software Foundation.

# P

Partition

  Hard disks and other similar devices can be "divided" into parts which, for all practical purposes, can be used as separate disks; these parts are called partitions. For example, you can create partitions of differrent types (e.g., `FAT32` used by Windows and `ext2` used by Linux) on the same disk, format them independently of each other, and so on.

  See Also: Device.

Password

  A string of typable characters (letters, numbers, punctuation marks, etc.) used to authenticate a user's identity. Required for logging in.

Process ID (PID)

  The ID number by which the system identifies individual processes. The first process to run on the system has PID 0.

  See Also: Process.

Pixel

  A single element, or "dot", on the computer's screen. A pixel's colour is made up of a mixture of red, green and blue light. Screen resolution is measured in pixels.

  See Also: Resolution.

Pointer

  See: Mouse cursor

Point-to-point protocol (PPP)

  A protocol allowing a computer to connect to a TCP/IP network via a modem. A PPP connection allows an ordinary home computer connected to a telephone line to become a part of the Internet

Postscript

  A language for desribing printed pages, developed by Adobe Corporation. Can be used to describe both graphics and text, black and white or color. Postscript is the de-facto standard for quality printing; almost all printing in UNIX is done by converting the data to be printed to Postscript before sending it to printer. If your printer does not have built-in Postscript capabilities, then your system is probably configured to convert Postscript to something you printer can print.

  Postscript files can also be saved to disk; they usually have extension `.ps`. There is a number of utilities for viewing Postscript files, such as `gv` or `ggv`.

Process

  A task run by the operating system. UNIX is a multitasking sytem, so at any given moment there are many processes running. Usually, each command or application you start is run as a new process; some applications may run several processes. In addition, there is also a number of system processes which run in the background to ensure proper functioning of the system.

  Each process has a unique ID number (PID). You can view the list of all the processes running on your system using `GNOME System monitor (gtop)` or `Ktop`. See the documentation for these applications for more information.

# R

Resolution

  A measurement indicating the height and width of the visible screen of a computer in pixels. Typical resolutions include 640x480, 800x600, 1024x768, 1280x1024.

Root directory

  The top level directory of a UNIX file system, containing all other files and directories. Root directory is denoted by a single slash (`/`).

  See Also: Filesystem.

Root (user)

  The privileged user on a UNIX system; has full control over the system and all files on it, including those of other users. Is typically used by system administartor for system maintenance.

  See Also: System administrator.

Root window

  The background of an X11 desktop, in which background images ("wallpaper") or running programs may be displayed.

RPM package

  A file containing in it in a packed form all the files comprising an application (executable files, documentation, configuration, etc.), plus some extra information about the application, such as a brief description and dependency information. The RPM format makes installing, un-installing, upgrading, and keeping track of the applications installed on your system very easy. There is a number of tools available for working with RPM packages, such as `gnorpm` or `Kpackage`. For those who prefer the command line, there is also the rpm command. See the documentation for these utilities or RPM's Web page for more information.

  RPM format was developed by Red Hat, Inc; the acronym RPM stands for RPM Package Manager.

# S

Screen

  The physical monitor device of a computer, consisting of a cathode ray tube, liquid crystal display, or similar means of displaying pixels; the visible picture displayed on the monitor.

Screensaver

  A program which blanks the screen or displays pretty or entertaining graphics after a period of inactivity on the console. Originally intended to prevent "burn-in" of images on older cathode-ray tubes, screensavers are now used primarily for entertainment purposes or to lock an unused terminal, requiring the user to enter a password to return to the normal display.

Script

  A program written in an interpreted language, i.e. a language where the commands are executed one by one as you enter them (as opposed to compiled languages, in which the whole program must first be translated into machine codes (compiled) to create an executable file). By far the most common type of scripts are shell scripts, which are simply sequences of shell commands. Other popular types of scripts are javascripts used in Web pages, perl scripts and Tcl/Tk scripts.

  See Also: Shell.

SCSI

  Small Computer System Interface; an interface for connecting various computer components, such as hard drives. Works faster than the more common IDE interface, but is more expensive, so it is used mostly on servers.

Segmentation fault (segfault)

  A program crash. More precisely, this is what happens when a program tries to access resources which do not belong to it; in such a case, for security reasons the operating system immediately kills the offending program. Segfaults are almost always caused by bugs in the program.

Shell

  Any of a number of UNIX programs which interpret commands typed by the user before passing them to the operating system and provide other features such as command history, aliasing, and scripting. Examples include bash and tcsh. Shells are often displayed in a terminal window.

SMTP

  Simple Mail Transfer Protocol; a protocol used for exchanging electronic mail messages between machines on a network.

Spam

  Useless e-mail. Spam normally comes in forms of chain-letters and advertisements for websites or services.

Symbolic link (symlink)

  A file of special type which contains no data but instead, points to another file or directory. Equivalent to a "shortcut" under Windows.

System administrator

  The person responsible for administration and maintenance of a computer system.

  See Also: Root (user).

# T

Tar archive (tarball)

  A file created using the tar (Tape ARchive) program, which conglomerates multiple files, or even a whole directory tree, into one file for easy storage or transfer. These archives are often compressed using the gzip program and given a filename extension of `.tar.gz`.

TCP/IP

  Transmission Control Protocol/Internet Protocol; pair of protocols used for all communication between computers on the Internet and most local networks. TCP/IP serves as a basis for higher level protocols (FTP, telnet, SMTP, …): all information sent from one computer to another on the Internet, be it an e-mail message or a Web page, is sent as a collection of TCP/IP packets.

Telnet

  A protocol allowing logging into your computer account via Internet or local network from another computer; also, the command using this protocol. For more information, see manual page for telnet.

Terminal

  Originally, a physical device, a monitor capable of showing text output with a connected keyboard. Nowadays, mostly used to refer to a window on your screen which emulates one of these terminals and provides a command line prompt for entering commands and running text-based applications.

Theme

  An integrated collection of graphical elements intended to give the desktop a certain look and feel. Common theme components include matching backgrounds, icons, and window decorations.

  The look of GNOME desktop is determined by 2 themes: a GTK theme, which determines the look of application menus, toolbars and other widgets, and window manager theme, which determines window borders, buttons, and window title font.

# U

Unicode

  A character set which strives to include all symbols in all human alphabets, and all special symbol used by people. It is a work in progress; the latest version of Unicode (3.0) includes 49,194 characters and covers languages ranging from English to Chinese to Cherokee. For more information, see Unicode Consortium Web site.

UNIX

  An operating system originally developed at Bell Labs in the early 1970s by Ken Thompson and Dennis Ritchie; any of a large number of operating systems sharing many features with the original UNIX operating system, such as Sun's Solaris or IBM's AIX.

  For legal reasons, operating systems such as FreeBSD and Linux can not be called UNIX, but they do share all important features with UNIX systems; thus, they are commonly called "UNIX-like".

USB

  Universal Serial Bus; an interface for connecting various peripherals, from keyboard to digital cameras, to the computer.

User

  An actual person who uses a computer system, identified by a unique username, or a virtual person or "role" similarly identified by a unique username. Virtual users may be used to run daemons or other software.

Username

  A string of alphanumeric characters uniquely identifying a user of a computer system. Most usernames are based on the user's real name, so Mary Smith might have the username "mary" or "msmith".

  See Also: login.

Uniform Resource Locator (URL)

  An "address", or "location", of a document. Most common URL types are a Web address (such as http://www.gnome.org), a file on a FTP server (e.g., ftp://ftp.gnome.org/pub), or a file on your own local system (e.g., file:/usr/doc/). Formal definition of URL (which is a subset of more general notion, Uniform Resource Identifier (URI)) is given in RFC2396, (beware: as any formal deinition, this one is way too technical for greater majority of users).

# V

Virtual desktop

  Some window managers allow the user to have several "virtual desktops";you could have application windows open and working on all of them, even though at every moment, only one of the virtual desktops is shown on your screen. Similar to having several physical desks in your office so that you can put your papers on all of them, even though you can only work at one desk at a time

  See Also: Workspace.

# W

Widget

  A single element of a graphical user interface, such as a button, scrollbar, or text input area.

Window

  The interface element used to display most applications under a windowing GUI such as X Window System. Windows typically consist of a main area in which typing or other work occurs, a title bar (which may contain buttons to minimize, maximize or close the window), window-specific menus, and a scroll bar down either side of the window if required.

Window manager

  A program which extends the capabilities of the X Window System by providing most of the user-friendly widgets people expect from a windowing system, such as window borders, buttons and menus, ways of moving, resizing, and hiding windows, placing the icons on your desktop, and so on. Examples of window managers include `Sawfish` and `Windowmaker`.

Workspace

  Same as virtual desktop.

World Wide Web (WWW)

  The most visible part of the Internet; the World Wide Web is formed by all the Web pages available on the Internet and all the links among them.

  See Also: HTML.

# X

X Window System

  A graphical system commonly used with UNIX operating systems; also known under the names X11 or simply X. X is responsible for putting windows, icons, text, and other graphical elements on your screen. X is always used in combination with window manager, which provides higher level functions such as moving, minimizing, and maximizing windows.

X11

  See: X Window System

XFree86

  A freely redistributable implementation of the X Window System that runs on UNIX-like operating systems (and OS/2). For more information, visit XFree86 Web page.

X server