I have alot of computer books. Alot. C, Java, Fortran, GIS, numerical algorithms, parallel computing....I can see 40 books from here as I type and I have just as many at my "real" office, and I have recycled enough of them to save a small forest.
This book is, hands down, the best I have ever bought. First, it is good value: 1500 pages, densely packed with information. No screen grabs of menus...just the facts and demo code. Second, it is authoritative. I am programming in C for an embedded POSIX Linux system and, so far, everything the book suggests works perfectly. It is more accurate and more helpful than any combo of web pages I have ever found, including those from the system manufacturer. Finally, it has some of the best C tutorial code I have ever seen...modern, clean, tight, and correct.
I am a relative newcomer to systems programming, and am not sure how much I will want to use systems calls v. standard C library routines...but this book provides both options. I highly recommend it for anyone who want to program in C and *may* want to use Linux system calls.