What is the best book to learn Linux system programming?

W. Richard Stevens: Advanced Programming in the UNIX Environment

The Linux Programming Interface by Michael Kerrisk

Note that the author is the current maintainer of the Linux man pages. And that it's not out yet so I can't actually say how good it is, but I've read the blog posts about it and it sounds like a good book. (and he is the maintainer of the man pages, and those are mostly well written and he ought to know his stuff)

EDIT: book is now out.

http://blog.man7.org/2009/07/whats-book-about.html

http://www.man7.org/tlpi/index.html

http://www.nostarch.com/linuxprogramming.htm

Linux Systems Programming

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