Programming with GNU Software

Linux is built on twin pillars. The one we usually associate with Linux is the kernel developed by Linus Torvalds. And the other, the one we often take for granted, is the set of GNU tools that make up the portable software development system from the Free Software Foundation (FSF). Programming with GNU Software is a brief but thoroughly useful introduction to these tools and how to use them. The tools covered are Emacs, the C and C++ compilers gcc and g++, the gdb debugger, the make utility, the RCS revision control system and gprof, a utility for profiling and timing your programs. The CD-ROM contains the sources for these tools and compiled binaries for several popular Unix systems such as SunOS and Solaris for SPARC, HP-UX for HP9000, AIX for the RS/6000, Irix for Indigo, and DEC Unix for the Alpha.

The book and CD-ROM combination is not specifically intended for Linux users, but this is an important book for anyone who develops software for Unix or Linux. This book was described as “forthcoming” in an O'Reilly catalog over a year ago and I have been eagerly awaiting it since then. If you have a recent distribution of Linux, you probably already have most or all of the tools discussed here. Even so, nearly everything in the book, and many of the sources on the CD-ROM, can be useful to Linux beginners and experts alike. A significant additional benefit is the discussion of cross-compilation and cross-development for a wide variety of platforms. If you are interested in portable software or porting applications, embedded systems, or just a good introduction to the GNU tools, this book is a good place to start.

The libraries on the CD-ROM are not the FSF versions governed by the LGPL (a General Public License for libraries). The libraries are rewritten versions from Cygnus Support, a company that ports and supports free software for commercial use, particularly in embedded systems. Using the Cygnus libraries avoids the more impractical restrictions of the LGPL for commercial embedded systems, and Cygnus requires only that you acknowledge use of their software. If you invent the world's greatest latte maker/bagel warmer, for example, and use the FSF libraries in the controller, you either have to make the source code available or provide a way for your customers to upgrade the libraries in case of a new release. If you have any questions about the legal issues, you should contact Cygnus Support. Check out their web site at http://www.cygnus.com/.

After an introduction and discussion of free software philosophy in Chapter 1, Chapter 2 offers a brief introduction to the use of Unix and its traditional tools for software development. Then Chapter 3 gets into the heart of GNU software with Emacs. If you have been intimidated by the sheer mass of Emacs, you should find this chapter an easy way to get started.

The coverage in this book is not simply introductory, but also has depth where it counts. Even though I've used versions of Emacs for years I learned several new tricks in this chapter. For example, I like to use the original Kernighan & Ritchie indentation style in my C programs, and indent by four spaces with each press of the TAB key. Using an example in the book, I was able to add a customization to my default initialization file, .emacsrc, in my home directory. Now, whenever I edit a file that ends in .c, .cpp or .h, Emacs will automatically be in C-mode, and will indent my programs properly when I press the TAB key at the beginning of a line. Most of its features and all of its customizations are written in Emacs Lisp. Emacs itself is mostly an interpreter for this language and its many extensions. Also covered is how to run the compiler from within Emacs, so you can continue editing while compilation proceeds in the background.

The GNU software tools are integrated and work together in a variety of ways, and Emacs is at the heart of it. Here are some additional incentives for learning and using Emacs I've gleaned from the book:

Because of the interoperability between Emacs, bash, gcc, GNU make, RCS and gdb, learning to use Emacs just makes good sense.