So the parent forks C, then forks B, then does A. When A is finished, then B and C will be reaped, meanwhile if they are already done then they are zombies.

Would be cleaner to:

if (!fork) { <process A>; exit }
if (!fork) { <process B>; exit }
if (!fork) { <process C>; exit }
# parent waits for A, B, and C
1 while wait() > 0;
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