Linux Application Development

• Michael K. Johnson,Erik W. Troan
• Addison-Wesley
• 0321219147

If I had to pick one word for this book, I'd choose "thorough". Give me the luxury of a few more words and I'd add "sumptuous", "enthralling" and maybe even "riveting". Well, OK, maybe "riveting" wouldn't be most folks choice, but I can really get into a well written book like this. From almost the very first page I learned things I never knew. What was even more interesting was learning the "why" behind things I already did know - that's where the "thorough" comes into play: you don't just learn the rules for Make's variable dereferencing, you learn why it works that way. Make doesn't get its own chapter, but it is explained in good depth, as are gdb and gcc itself.

After that, and a good overview of the GNU C library. there's a great chapter on memory debugging and the various tools available to help find your errant pointers. I don't program much in C anymore, so I was mostly unaware of these tools and certainly didn't understand the features and limitations that this chapter covered. After that, it's on to building and using shared libraries, with lucid explanation of the role of ldconfig and how sonames are linked to real libraries. Preloading libraries is covered using the example of zlibc, which was another thing I never knew existed (it can automagically uncompress files so that programs written with standard C "open" work transparently with zipped files).

Then we have the meat of the book, covering Linux system calls, file handling, signals, etc. A "ladsh" (Linux Application Development Shell) is presented and used as an example throughout. Networking, psuedo tty's, date and time, random numbers, programming the virtual consoles - it's all here, and all well illustrated by excellent examples and sample code.

I was very pleased to see a full chapter on security. That's too often overlooked in programming books. That chapter is thorough also, even noting how preloading libraries or setting NLSPATH could be used to compromise setuid/setgid programs.

The final section of the book turns to development libraries (string handling, regexes, etc.). There I found yet another of the many things I had no knowledge of: the S-Lang library for terminal handling. In the chapter on dbm files, I learned about qdbm, an LGPL library for hashed databases. The final chapters cover dynamic loading and PAM.

I have neither the time nor the mental stamina to do C programming any more, but books like this make me wish that I did. Not that I'm any good at it, but there is tremendous statisfaction in crafting lower level programs that bend the system to your will. But beyond that, understanding HOW the lower level stuff all works can help you write better programs at a higher level and understand what they are really doing (which can be a great aid in debugging). So this book will be one I pick up and re-read regularly.

Tony Lawrence 2005/01/04 Rating: 5.0

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