Bell Labs distributed the operating system in its source language form, so anyone who obtained a copy could modify and customize it for his own purposes. By the end of the 1970s, dozens of different versions of UNIX were running at various sites.
Flavours of Unix:
Unix is not a single operating system. It has branched out in many di.erent directions since it was introduced by AT&T. The most important `fork()' in its history happened early on when the university of Berkeley, California created the BSD (Berkeley Software Distribution), adding network support and the C-shell.
Here are some of the most common implementations of unix.
BSD : Berkeley, BSD
SunOS : Sun Microsystems, BSD/sys 5
Solaris : Sun Microsystems, Sys 5/BSD
Ultrix : Digital Equipment Corperation, BSD
OSF 1 : Digital Equipment Corperation, BSD/sys 5
HPUX : Hewlett-Packard, Sys 5
AIX : IBM, Sys 5 / BSD
IRIX : Silicon Graphics, Sys 5
GNU/Linux : GNU, BSD/Posix