All of the information about a user, including username, password, finger information, UID and GID, and home directory. To create an account is to add and define a user.


Any process that is running without accepting or controlling the input of a terminal is said to be running in the background.

Boot disk

A floppy disk containing an operating system (in our case, the Linux kernel) from which a computer can be started.


To convert source code to machine-readable “binary” code.


A program designed to run in the background and, without user intervention, perform a specific task (usually providing a service).


The default hostname in Slackware; your computer will be called darkstar if you do not specify some other name.

One of Patrick Volkerding's development machines, named after “Dark Star”, a song by the Grateful Dead.

Desktop Environment

A graphical user interface (GUI) that runs atop the X Window System and provides such features as integrated applications, cohesive look-and-feel between programs and components, file and window management capabilities, etc. A step beyond the simple window manager.

Device driver

A chunk of code in the kernel that directly controls a piece of hardware.

Device node

A special type of file in the /dev filesystem that represents a hardware component to the operating system.


Domain Name Service. A system in which networked computers are given names which translate to numerical addresses.

Domain name

A computer's DNS name, excluding its host name.

Dot file

In Linux, files which are to be hidden have filenames beginning with a dot ('.').

Dotted quad

The format of IP addresses, so called because it consists of four numbers (range 0-255 decimal) separated by periods.

Dynamic loader

When programs are compiled under Linux, they usually use pieces of code (functions) from external libraries. When such programs are run, those libraries must be found and the required functions loaded into memory. This is the job of the dynamic loader.

Environment variable

A variable set in the user's shell which can be referenced by that user or programs run by that user within that shell. Environment variables are generally used to store preferences and default parameters.


A period of history; in Unix, “The Epoch” begins at 00:00:00 UTC January 1, 1970. This is considered the “dawn of time” by Unix and Unix-like operating systems, and all other time is calculated relative to this date.


A representation of stored data in which “files” of data are kept organized in “directories”. The filesystem is the nearly universal form of representation for data stored to disks (both fixed and removable).


A program that is accepting or controlling a terminal's input is said to be running in the foreground.


A type of graphics device; in Linux, this most often refers to the software framebuffer, which provides a standard framebuffer interface to programs while keeping specific hardware drivers hidden from them. This layer of abstraction frees programs of the need to speak to various hardware drivers.


The File Transfer Protocol. FTP is a very popular method of transferring data between computers.


A computer through which data on a network is transferred to another network.


Group Identifier. The GID is a unique number attributed to a group of users.


Users in Unix belong to “groups”, which can contain many other users and are used for more general access control than the existence of users alone can easily allow.


Graphical User Interface. A software interface that uses rendered graphical elements such as buttons, scrollbars, windows, etc. rather than solely text-based input and output

Home directory

A user's “home directory” is the directory the user is placed in immediately upon logging in. Users have full permissions and more or less free reign within their home directories.


A document describing “how to” do something, such as configure a firewall or manage users and groups. There is a large collection of these documents available from the Linux Documentation Project.


The Hypertext Transfer Protocol. HTTP is the primary protocol on which the World Wide Web operates.


Internet Control Message Protocol. A very basic networking protocol, used mostly for pings.


The heart of an operating system. The kernel is the part that provides basic process control and interfaces with the computer's hardware.

Kernel module

A piece of kernel code, usually a driver of some sort, that can be loaded and unloaded from memory separately from the main body of the kernel. Modules are handy when upgrading drivers or testing kernel settings, because they can be loaded and unloaded without rebooting.


A collection of functions which can be shared between programs.


The LInux LOader. LILO is the most widely-used Linux boot manager.


LOADLIN is a program that runs under MS DOS or Windows and boots a Linux system. It is most commonly used on computers with multiple operating systems (including Linux and DOS/Windows, of course).

Man section

Pages in the standard Unix online manual ("man") are grouped into sections for easy reference. All C programming pages are in section 3, system administration pages in section 5, etc.


The Master Boot Record. A reserved space on a hard drive where information on what to do when booting is stored. LILO or other boot managers can be written here.


A popular programming toolkit used in many older X programs.


Message of the Day. The motd (stored in Linux in /etc/motd is a text file that is displayed to all users upon logging in. Traditionally, it is used by the system administrator as a sort of “bulletin board” for communicating with users.

Mount point

An empty directory in a filesystem where another filesystem is to be “mounted”, or grafted on.


A DNS information server. Nameservers translate DNS names to numerical IP addresses.

Network interface

A virtual representation of a network device provided by the kernel. Network interfaces allow users and programs to talk to network devices.


The Network Filesystem. NFS allows the mounting of remote filesystems as if they were local to your computer and thus provides a transparent method of file sharing.


Base-8 number system, with digits 0-7.


An X program that allows the user to see and switch between multiple “desktops”.


A division of a hard drive. Filesystems exist on top of partitions.


Point-to-Point Protocol. PPP is used mainly for connecting via modem to an Internet Service Provider.


A running program.

Root directory

Represented as “/”, the root directory exists at the top of the filesystem, with all other directories branching out beneath it in a “file tree”.

Root disk

The disk (usually fixed) on which the root directory is stored.

Routing table

The set of information the kernel uses in “routing” network data around. It contains such tidbits as where your default gateway is, which network interface is connected to which network, etc.


The overall system state as defined by init. Runlevel 6 is rebooting, runlevel 1 is “single user mode”, runlevel 4 is an X login, etc. There are 6 available runlevels on a Slackware system.

Secure shell

An encrypted (thus secure) method of logging in remotely to a computer. Many secure shell programs are available; both a client and server are needed.


The sharing of information and/or data between programs and computers from a single “server” to multiple “clients”. HTTP, FTP, NFS, etc. are services.

Shadow password suite

The shadow password suite allows encrypted passwords to be hidden from users, while the rest of the information in the /etc/passwd file remains visible to all. This helps prevent brute-force attempts at cracking passwords.


Shells provide a commandline interface to the user. When you're looking at a text prompt, you're in a shell.

Shell builtin

A command built into the shell, as opposed to being provided by an external program. For instance, bash has a cd builtin.


Unix programs can communicate between each other using simple “signals”, which are enumerated and usually have specific meanings. kill -l will list the available signals.


Serial Line Interface Protocol. SLIP is a similar protocol to PPP, in that it's used for connecting two machines via a serial interface.

Software package

A program and its associated files, archived and compressed into a single file along with any necessary scripts or information to aid in managing the installation, upgrade, and removal of those files.

Software series

A collection of related software packages in Slackware. All KDE packages are in the “kde” series, networking packages in the “n” series, etc.

Source code

The (more or less) human-readable code in which most programs are written. Source code is compiled into “binary” code.

Standard Error (stderr)

The Unix-standard output stream for errors. Programs write any error messages on stderr, so that they can be separated from normal output.

Standard Input (stdin)

The Unix-standard input stream. Data can be redirected or piped into a program's stdin from any source.

Standard Output (stdout)

The Unix-standard output stream. Normal text output from a program is written to stdout, which is separate from the error messages reported on stderr and can be piped or redirected into other programs' stdin or to a file.


An IP address range that is part of a larger range. For instance, is a subnet of (where 0 is a mask meaning “undefined”); it is, in fact, the “.1” subnet.


In Linux, partitions are discussed in terms of blocks. A block is 512 bytes. The superblock is the first 512 bytes of a partition.

Supplemental disk

In Slackware, a floppy disk used during installation that contains neither the kernel (which is on the boot disk) nor the root filesystem (which is on the root disk), but additional needed files such as network modules or PCMCIA support.

Suspended process

A process which has been frozen until killed or resumed.

Swap space

Disk space used by the kernel as “virtual” RAM. It is slower than RAM, but because disk space is cheaper, swap is usually more plentiful. Swap space is useful to the kernel for holding lesser-used data and as a fallback when physical RAM is exhausted.

Symbolic link

A special file that simply points to the location of another file. Symbolic links are used to avoid data duplication when a file is needed in multiple locations.


A file used by the Slackware setup program during installation, which describes a set of packages to be installed.


A human-computer interface consisting of at least a screen (or virtual screen) and some method of input (almost always at least a keyboard).

Toolkit, GUI

A GUI toolkit is a collection of libraries that provide a programmer with code to draw “widgets” such as scrollbars, checkboxes, etc. and construct a graphical interface. The GUI toolkit used by a program often defines its “look and feel”.


User Identifier. A unique number that identifies a user to the system. UIDs are used by most programs instead of usernames because a number is easier to deal with; usernames are generally only used when the user has to see things happen.


Video Electronics Standards Association. The term “VESA” is often used to denote a standard specified by said Association. Nearly all modern video adapters are VESA-compliant.

Virtual terminal

The use of software to simulate multiple terminals while using only a single set of input/output devices (keyboard, monitor, mouse). Special keystrokes switch between virtual terminals at a single physical terminal.

Window manager

An X program whose purpose is to provide a graphical interface beyond the simple rectangle-drawing of the X Window System. Window managers generally provide titlebars, menus for running programs, etc.

Working directory

The directory in which a program considers itself to be while running.

Wrapper program

A program whose sole purpose is to run other programs, but change their behavior in some way by altering their environments or filtering their input.

X server

The program in the X Window System which interfaces with graphics hardware and handles the actual running of X programs.

X Window System

Network-oriented graphical interface system used on most Unix-like operating systems, including Linux.