CUPS provides a portable printing layer for UNIX(r)-based operating
systems. CUPS provides the System V and Berkeley command-line
interfaces.
CUPS uses the Internet Printing Protocol ("IPP") as the basis for
managing print jobs and queues. The Line Printer Daemon ("LPD") Server
Message Block ("SMB"), and AppSocket (a.k.a. JetDirect) protocols are
also supported with reduced functionality. CUPS adds network printer
browsing and PostScript Printer Description ("PPD") based printing
options to support real-world printing under UNIX.
WWW: http://www.cups.org/