Below are additional sources of information about proc file system.
Some of the best documentation about the proc file system is installed on the system by default.
/usr/share/doc/kernel-doc-kernel_version/Documentation/filesystems/proc.txt — Contains assorted, but limited, information about all aspects of the /proc/ directory.
/usr/share/doc/kernel-doc-kernel_version/Documentation/sysrq.txt — An overview of System Request Key options.
/usr/share/doc/kernel-doc-kernel_version/Documentation/sysctl/ — A directory containing a variety of sysctl tips, including modifying values that concern the kernel (kernel.txt), accessing file systems (fs.txt), and virtual memory use (vm.txt).
/usr/share/doc/kernel-doc-kernel_version/Documentation/networking/ip-sysctl.txt — A detailed overview of IP networking options.
http://www.linuxhq.com/ — This website maintains a complete database of source, patches, and documentation for various versions of the Linux kernel.
