Berkeley printing system
The Berkeley printing system is one of several standard architectures for printing on the Unix platform. It originated in 2.10BSD, and is still used to varying degrees in BSD derivatives such as FreeBSD, NetBSD, OpenBSD, and DragonFly BSD. A system running this print architecture could traditionally be identified by the use of the user command lpr as the primary interface to the print system, as opposed to the System V printing system lp command.