In article <1078871806.413261.13912.nullmailer / picachu.netlab.jp>,
  matz / ruby-lang.org (Yukihiro Matsumoto) writes:

>   * what platforms are they available?  linux man says wait3 and wait4
>     are defined in POSIX.1.

wait3 is defined in SUSv2 but marked as legacy.
wait3 is not defined in SUSv3.

wait4 is not defined in SUSv2 and SUSv3.

wait3 and wait4 are not defined in IEEE 1003.1 1996-07-12 (POSIX.1).

SUSv2 said "New applications should use waitpid()."
waitpid cannot be used to get rusage, though.
-- 
Tanaka Akira