Ever since the /proc file system first made an appearance on Unix systems, getting information on running processes became a whole lot easier. The useful, but too often insufficient information available in the output of ps commands was thoroughly upstaged by /proc which acts as an interface to kernel data structures. /proc provides interfaces to kernel data structures that can supply information on how memory is being used, what devices are mounted, which file descriptors are in use, and what command line arguments were used with running processes — and that’s just a start.