Perhaps rovf's machine is one of the machines that doesn't?
It's Windows 2000, but the code is also supposed to run on Windows XP.
Second, it isn't entirely clear how one would write a program to use a non-blocking wait, assuming there is one.
Indeed I see from the perldocs only that waitpid accepts flags, but there is no description of what the possible value of these flags might be...

-- 
Ronald Fischer <ynnor@mm.st>

In reply to Re^3: Testing whether a process has finished by rovf
in thread Testing whether a process has finished by rovf

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