Linux is a freely-distributed UNIX system (OS, utilities, and applications) for PCs. Linux is a straightforward POSIX version of UNIX with many utilities drawn from the GNU and BSD systems. The file system is highly configurable and seems to be closer to System V rather than BSD. Most commands, however, look like BSD commands. The feel of the user environment is similar to a Sun under SunOS. Additionally, Linux supports a wealth of standard PC and UNIX hardware.
The Linux and GNU tools are documented by man pages, GNU ``info'' hypertext manuals, and HTML-format ``HOWTO'' pages, and supported (in many cases by their authors) on public newsgroups. The help that we received through newsgroups during our port to Linux was prompt and accurate. Finally, several fine books Welsh and Kaufman (1996) on Linux are available in a good technical bookstore.
While our experience and this note are limited to Linux on PC hardware, Linux is cross-platform. It is available now for SPARC and DEC Alpha machines and ports are under way to PowerMacs and MIPS machines.