Datasheet

Chapter 1: What is Ubuntu?

The bash shell was developed by the GNU project as a replacement for the standard UNIX

shell, called the Bourne shell (after its creator, Stephen Bourne). The bash shell name is

a play on this wording, referred to as the Bourne-again shell.

Besides the bash shell there are several other popular shells that Ubuntu supports.

Table 1-2 lists the more popular shells available in Ubuntu.

Table 1-2: Linux Shells

Shell Description

ash A simple, lightweight shell that runs in low-memory environments but has full com-

patibility with the bash shell

korn A programming shell compatible with the Bourne shell, but supporting advanced pro-

gramming features such as associative arrays and ﬂoating-point arithmetic

tcsh A shell that incorporates elements from the C programming language into shell

scripts

zsh An advanced shell that incorporates features from bash, tcsh, and korn, providing

advanced programming features, shared history ﬁles, and themed prompts

Most Linux distributions include more than one shell, although usually they pick one

of them as the default. Ubuntu installs only the bash shell by default, but the others are

available to download and install (see Chapter 13, “Software Installs and Updates”).

The Linux Desktop Environment

In the early days of Linux (the early 1990s), all that was available was a simple text inter-

face to the Linux operating system. This text interface allowed administrators to start

programs, control program operations, and move ﬁles around on the system.

With the popularity of Microsoft Windows, computer users expected more than the old

text interface to work with. This expectation spurred more development in the OSS com-

munity, and the advent of Linux graphical desktops emerged.

Linux is famous for being able to do things more than one way, and no place is this fea-

ture more relevant than graphical desktops. You can choose from a plethora of graphical

desktops in Linux. The following sections describe a few of the more popular ones.

The X Windows System

There are two basic elements that control your video environment—the video card in your

PC and your monitor. To display fancy graphics on your computer, the Linux software

needs to know how to talk to both of them. The X Windows software is the core element

in presenting graphics.

The X Windows software is a low-level program that works directly with the video card

and monitor in the PC. It controls how Linux applications can present fancy windows and

graphics on your computer.

Linux isn’t the only operating system that uses X Windows; there are versions written for

many different operating systems. In the Linux world, only two software packages can

implement X Windows.

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