CITS2002 Systems Programming  
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The general calling sequence of system calls

If a single program has two distinct execution paths/sequences, then the parent and child may run different parts of the same program. Typically the parent will want to know when the child terminates.


The typical sequence of events is:

  • the parent process fork()s a new child process.

  • the parent waits for the child's termination, calling the blocking function wait( &status ).

  • [optionally] the child process replaces details of its program (code) and data (variables) by calling the execve() function.

  • the child calls exit(value), with an integer value to represent its success or failure. By convention, zero (= EXIT_SUCCESS) indicates successful execution, non-zero otherwise.

  • the child's value given to exit() is written by the operating system to the parent's status.

 


CITS2002 Systems Programming, Lecture 9, p3, 19th August 2024.