Question

In UNIX, the return value for the fork system call is _____ for the child process and _____ for the parent process.

(a) A Negative integer, Zero

(b) Zero, A Negative integer

(c) Zero, A nonzero integer

(d) A nonzero integer, Zero

This question was posed to me in a national level competition.

This question is from Process Creation in chapter Processes of Operating System

Answer 1

Right option is (c) Zero, A nonzero integer

The explanation is: In Unix, the return value of the fork system call is Zero for the child process and Non-zero value for parent process. A fork system call returns the PID of a newly created (child) process to the parent and returns Zero to that newly created (child) process.