Wikipedia
LinuxCNC
LinuxCNC (formerly "Enhanced Machine Controller" or "EMC2") is a free, open-source GNU/Linux software system that implements numerical control capability using general purpose computers to control CNC machines. Designed by various volunteer developers at linuxcnc.org, it is typically bundled as an ISO file with a modified version of 32-bit Ubuntu Linux which provides the required real-time kernel.
Due to the tight real-time operating system integration, a standard Ubuntu Linux desktop PC without the real-time kernel will only run the package in demo mode.