Here are some places to visit on the Internet to learn more about programming for the GNU/Linux system.
http://www.advancedlinuxprogramming.com is this book’s home on the Internet. Here, you can download the full text of this book and program source code, find links to other online resources, and get more information about programming GNU/Linux.
http://www.tldp.org is the home of the Linux Documentation Project. This site is a repository for a wealth of documentation, FAQ lists, HOWTOs, and other documentation about GNU/Linux systems and software.
Information about GNU/Linux software
http://www.gnu.org is the home of the GNU Project. From this site, you can download a staggering array of sophisticated free software applications. Among them is the GNU C library, which is part of every GNU/Linux system and contains many of the functions described in this book. The GNU Project site also provides information about how you can contribute to the development of the GNU/Linux system, by writing code or documentation, by using free software, and by spreading the free software message.
http://www.kernel.org is the primary site for distribution of the Linux kernel source code. For the trickiest and most technically detailed questions about how Linux works, the source code is the best place to look. See also the Documentation directory for explanation of the kernel internals.
http://www.linuxhq.com also distributes Linux kernel sources, patches, and related information.
gcc.gnu.org is the home of the GNU Compiler Collection (GCC). GCC is the primary compiler used on GNU/Linux systems, and includes compilers for C, C++, Objective C, Java, Chill, and Fortran.
http://www.gnome.org and http://www.kde.org are the homes of the two most popular GNU/Linux windowing environments, Gnome and KDE. If you plan to write an application with a graphical user interface, you should familiarize yourself with either or both.
developer.intel.com provides information about Intel processor architectures, including the x86 (IA32) architecture. If you are developing for x86 Linux and use inline assembly instructions, the technical manuals available here will be very useful.
http://www.amd.com/devconn/ provides similar information about AMD’s line of microprocessors and their special features.
freshmeat.net is an index of open source software, generally for GNU/Linux. This site is one of the best places to stay abreast of the newest releases of GNU/Linux software, from core system components to more obscure, specialized applications.
http://www.linuxsecurity.com contains information, techniques, and links to software related to GNU/Linux security. The site is of interest to users, system administrators, and developers.