How strictly do you mean “UNIX clone”? Because Linux isn’t strictly UNIX. But then at the other end of the scale, BeOS was also partially POSIX compliant and shipped with Bash plenty of UNIX CLI tools.
Perhaps it’s better to play it safe and just run DOS instead ;)
BeOS on its final commercial version certainly did not allow to compile UNIX applications, beyond the common surface that is part of ISO C and ISO C++ standard library.
maybe in early BeOS versions but, BeOS R5 especially with the BONE updates had a fairly decent POSIX compatibility for the time. If you do "ls /" you can see immediatly BeOS has some BSD reminiscence, but certainly it isn't a UNIX OS as in itself.
