sunos:
SunOS is a version of the Unix operating system developed by Sun Microsystems for their workstation and server computer systems. The SunOS name is usually only used to refer to versions 1.0 to 4.1.4 of SunOS. These versions were based on BSD, while SunOS version 5.0 and later are based on UNIX System V Release 4, and are marketed under the brand name Solaris.