Glossary

ADSL - Asymmetric Digital Subscriber Line

ADSL is a technology for transmitting digital data across normal copper phone lines at high speeds. It is a short-range technology, requiring subscribers to be within a few kilometres of the exchange providing the service. It is called Asymmetric because download speeds are configured to be far higher than upload speeds (you can receive more quickly than you can send).

API - Application Programming Interface

Just as a program has a range of menus, icons and buttons with which a user can control it, it can have a set of method calls and data structures that can be used by other programs to control it. This is the API.

BIOS - Basic In/Out System

A small program in non-volatile storage that is executed immediately after a computer is powered up. Normally, it passes control to the boot loader of the selected boot media as soon as possible. However, it also displays some diagnostic information while executing, including a prompt to enter configuration mode. While in configuration mode, you may set various basic properties of the computer, such as the time of the system clock and the selected boot media (e.g. CD-ROM, hard disk, or network).

Boot

When a computer is powered up, control immediately passes to the BIOS. The BIOS finds the program code that should be executed to continue the startup process, until the operating system is up and running. The whole procedure is called booting up, from the expression "pulling yourself up by your bootlaces". Picture a cartoon figure on flat land, grabbing hold of his bootlaces and pulling himself up into the air until he's flying. A computer manages something similar, when it changes from an inert lump of plastic to a running system.

CA - Change Agent

Person who takes on the role of institutional change

CGI - Common Gateway Interface

This is a specification for calling scripts that are triggered through the web. The CGI standard specifies what data must be passed to the script.

Client

Computer system or process used in conjunction with a server.

CPU - Central Processing Unit

The CPU is the core of the computer. It's one of the smaller pieces, consisting of a flat square of silicon, but it contains most of the computer's complexity, in the form of millions of transistors. When the computer is executing programs, all of the instructions as well as the data are fetched from RAM and processed by the CPU.

Daemon

A program that runs on a server, waiting for requests and servicing them. The program runs permanently, as long as the service should be offered.

DHCP - Dynamic Host Configuration Protocol

This server auto-configures network settings automatically on clients using DHCP. DHCP is very commonly used across many platforms, including many Unix variants, MacOS, and Microsoft Windows.

DNS - Domain Name Server

The Domain Name System is part of the core infrastructure of the Internet. It consists of a massive globally distributed database that matches IP addresses (e.g. 216.239.57.99) to domain names that humans like to remember (e.g. google.com). As long as they keep to the rules, anyone can run a DNS server to resolve local address and to cache global addresses. No DNS server needs to store all the domain names on earth: the job is distributed among ISPs who each take responsibility for different sections of the namespace. If your local nameserver doesn't know an IP address, it knows who to ask to get an answer. If DNS is unavailable, all the services that depend on it (such as web browsing and email) don't work.

DOM - Document Object Model

When a web browser parses an HTML page, it doesn't just write out text to the screen and have done with it. It needs to hold on to the entire structure in order to be able to rewrite it using Javascript, changing parts of the page in-place and reflowing the resulting document immediately. This internal structure is called the Document Object Model. You can read all about it at the World Wide Web Consortium's Document Object Model page.

Dumb Terminal

A dumb terminal is a workstation that does no local processing. Dumb terminals generally only echo's characters sent over a serial line, and is different to a LTSP thin client.

Edubuntu WebLive

Edubuntu WebLive is a feature on the Edubuntu website that allows users to try out an Edubuntu desktop without even having to download the Edubuntu installation media. It doesn't provide administrator access, so it has some limitations compared to a Live DVD. Some features such as Nanny and Pessulus does not work on Edubuntu WebLive.

FIPS - Federal Information Processing Standards

U.S. Government organization that collects and distributes standard documents and methods

ISP - Internet Service Provider

A business which provides Internet access to its customers. The nature of this service may vary widely, from dialup access and email for home users to wireless broadband and website hosting for big media companies and everything in between.

LDAP - Lightweight Directory Access Protocol

LDAP is a networking protocol for querying and modifying directory services running over the internet. It is a type of database used commonly for keeping accounts (usernames, passwords, groups, etc.) in.

LBE - LTSP Build Environment

LBE is what the LTSP project used to build the chroot before Muekow.

LTSP - Linux Terminal Server Project

LTSP is a collection of tools that can be used to boot machines on the network to a central server, without needing any local storage on the local machine.

LTSP Live

LTSP Live is a feature on the Edubuntu Live disc. It allows a user to demonstrate LTSP without performing any permanent changes to a system. It is useful to people who would like to try out LTSP or who would like to demonstrate it to other people.

Muekow

The project to create the latest version of LTSP. In use by Edubuntu as of version 5.10.

MAC Address - Media Access Control Device

In computer networking, a MAC address is a code on most forms of networking equipment that allows for that device to be uniquely identified.

Netmask

The netmask specifies all the IP addresses that belong to a particular network.

NFS - Network File System

A local filesystem reads data from a hard disk. NFS is a protocol that allows a remote filesystem to be mounted on a path of the local filesystem, so that data read from files on that path is not read from a local disk, but from a server on the network.

POST - Power On Self Test

The POST is a series of hardcoded self-tests that a computer's BIOS performs to see whether basic resources such as its CPU, memory, and keyboard are present and functional.

PROM - Programmable ROM

This is a kind of memory that can be written exactly once. After it's been written, its contents is fixed. It's generally used for things like network cards with the facility to boot from the network. Such cards can be used in many different environments, requiring different software. However, once deployed in some environment, it normally stays there. Therefor the required software can be written to a PROM on the card, effectively locking down the card to the deployed environment.

PXE - Pre-boot eXecution Environment

A small program on the network card that allows a computer to boot from the network. The PXE takes care of finding a server from which to boot, and transferring the boot loader from the server to the client across the network. See also: Etherboot

RAM - Random Access Memory

Random Access Memory ( RAM) Memory that stores code and data only as long as the computer is powered up. At the first hint of a power interruption, RAM becomes as blank as a beach washed clean by the tide. RAM can be written to, and during execution, programs are continuously rewriting its contents.

RAM disk

A RAM disk emulates a hard disk using the computer's memory. Whereas a hard disk stores data permanently until it is rewritten, a RAM disk only exists as a running program, and goes away when the program stops or the computer is powered down.

ROM - Read Only Memory

Memory that stores code and data permanently, whether or not the workstation is powered up. It cannot be written to: every time it's read, it's exactly the same.

root

In Edubuntu, there are three different references to 'root'.

(a) The root directory: This is the top level directory on your Edubuntu system, "/".
(b) The root user: root is a super administrator user (often refered to as 'the super user'), often used in Linux distributions for administration purposed. In Ubuntu, administrative access is gained by the sudo command. See also: sudo
(c) The root home directory: The root user's home directory is in /root. Even though it should theoretically never be used in Edubuntu, it's best to leave this directory alone (ie. not delete it).

RTFM - Read the FINE Manual

Linux is a self-documenting system. All Linux programs come with technical documentation, and most commands accept a --help option that will start you off. The information is sometimes cryptic, or just very dense, but if you don't read it two, three, four or five times, you'll find yourself asking the same questions again and again, and never progressing beyond the basics. You'll also find that people answer your questions with a terse "RTFM!", meaning that the answer is right there in the manual. Don't take offence, look it up.

SD - System Description

Document that describes a technology system. Used in the proposal process.

Server

Computer system or process used in conjunction with a client.

Shell

Another metaphor used to express the structure of a Linux system is that of a nut containing a kernel. The kernel is hidden inside, it is surrounded by a shell. As user you can't interact with the kernel directly, you interact with a shell program. This is a program which accepts commands and gives feedback, all via a textual command line interface. The shell has a number of builtin commands, but it also does job control, starting and stopping programs that run under its control. The shell has a full complement of flow control structures, so that it can be used to write programs. These are called shell scripts. Shell scripts are most often used to coordinate the execution of other programs.

SMTP - Simple Mail Transfer Protocol

When you send an email, your mail server looks at the headers of the mail to see where it should be delivered. It then uses DNS to look up the IP address of the mail server on the receiving end. When it knows whom to contact, it starts an SMTP conversation with the remote mailserver. It asks the server what version of the protocol it supports (so that it knows how to encode the mail, if necessary) and whether the server is accepting mail for the user you want to reach. When the two servers have gotten to know one another, the mail is transferred and queued for the remote user to read.

Symlink - Symbolic Link

A file can only be stored in one place on a disk. If you want it to appear to be in other places as well, you can make a symbolic link from there to the real location of the file. By most commands, the link will be transparent: it will be treated exactly as though the file really exists in that location.

Thin Client

Thin clients are machines that do very little local processing, usually only to display a graphical user interface. Thin clients are usually diskless, and connect to the server using technologies such as XDMCP, VNC, FreeNX, rdesktop or ssh. In Edubuntu, ssh is used for it's stability and security.

Ubiquity

Ubiquity is the Ubuntu installer, also used to install the Edubuntu system.

Weblive

See: Edubuntu WebLive