lpr command is used on many Unix-like systems to assign jobs to printer queues. The name derives from "lineprinter", though it has become the commonly used command for any sort of printer. The command originally appeared as part of the Berkeley printing system, and for some time served as a shibboleth to distinguish between System V and BSD systems.
lpr is the standard name for the BSD printer command. It is also the standard name for the printer command in the LPRng project. The Common Unix Printing System, used on Linux and Mac OS X among other systems, provides an
lpr command for compatibility with BSD systems. Microsoft Windows provides an
lpr command that prints to printers supporting the Line Printer Daemon protocol.
-  The program's manpage as implemented on CUPS systems