http://www.fmi.uni-passau.de/archive/doc/unix/unixhelp/Unixhelp/tasks_lpr2.2.html (Einblicke ins Internet, 10/1995)You can print PostScript files to a PostScript printer with the standard lpr command:
lpr filename
A PostScript printer will automatically recognises that the file consists of PostScript commands and processes it them accordingly.