The ps command is different on BSD and AT&T UNIX. On AT&T UNIX, the command to list all processes is:

ps –ef

On BSD UNIX and Linux, the command is

ps –aux

Write a program called systype that will check for a number of different system types. The cases to test for will be

AIX

Darwin (Mac OS X)

Free BSD

HP-UX

IRIX

Linux

OS

OSF1

SCO

SunOS (Solaris / SunOS)

ULTRIX

Solaris, HP-UX (10.x+), SCO, and IRIX are AT&T-type systems. The rest are BSD-ish.

The version of UNIX/Linux you are using will be printed to stdout. The system name can be found with the uname –s command or from the /etc/motd file.