Datasheet

A few major examples of software from the GNU Project distributed under the GPL follow:

❑ GCC: The GNU Compiler Collection, containing the GNU C compiler

❑ G++: A C++ compiler, included as part of GCC

❑ GDB: A source code–level debugger

❑ GNU make: A version of UNIX

make

❑ Bison: A parser generator compatible with UNIX yacc

❑ bash: A command shell

❑ GNU Emacs: A text editor and environment

Many other packages have been developed and released using free software principles and the GPL,

including spreadsheets, source code control tools, compilers and interpreters, Internet tools, graphical

image manipulation tools such as the Gimp, and two complete object-based environments: GNOME and

KDE. We discuss GNOME and KDE in Chapters 16 and 17.

There is now so much free software available that with the addition of the Linux kernel it could be said

that the goal of a creating GNU, a free UNIX-like system, has been achieved with Linux. To recognize the

contribution made by GNU software, many people now refer to Linux systems in general as

GNU/Linux.

You can learn more about the free software concept at

http://www.gnu.org.

Linux Distributions

As we have already mentioned, Linux is actually just a kernel. You can obtain the sources for the kernel

to compile and install it on a machine and then obtain and install many other freely distributed software

programs to make a complete Linux installation. These installations are usually referred to as Linux sys-

tems, because they consist of much more than just the kernel. Most of the utilities come from the GNU

Project of the Free Software Foundation.

As you can probably appreciate, creating a Linux system from just source code is a major undertaking.

Fortunately, many people have put together ready-to-install distributions (often called flavors), usually

downloadable or on CD-ROMs or DVDs, that contain not just the kernel but also many other program-

ming tools and utilities. These often include an implementation of the X Window System, a graphical

environment common on many UNIX systems. The distributions usually come with a setup program

and additional documentation (normally all on the CD[s]) to help you install your own Linux system.

Some well-known distributions, particularly on the Intel x86 family of processors, are Red Hat

Enterprise Linux and its community-developed cousin Fedora, Novell SUSE Linux and the free

openSUSE variant, Ubuntu Linux, Slackware, Gentoo, and Debian GNU/Linux. Check out the

DistroWatch site at

http://distrowatch.com for details on many more Linux distributions.

Programming Linux

Many people think that programming Linux means using C. It’s true that UNIX was originally written

in C and that the majority of UNIX applications are written in C, but C is not the only option available to

Chapter 1: Getting Started

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