What does the fork() system call return to the child process when it succeeds?
Correct answer A. 0
Explanation
On success fork() returns twice: the parent receives the new child's PID, while the child receives 0. This difference is how the code tells which copy it is running in. A return of -1 occurs only in the parent when the call fails and no child is created. The child can obtain its parent's PID with getppid() rather than from fork().
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