source: liacs/os/assignment1/parent1.c@ 28

/* a simple parent; version1; sys name: parent1.c
Now we better create a program, which will replace the replica
of the parent. We have named this replacing program child1.c
and have made an executable out of it carrying the name child1
(use the -o option). In parent process fork() returns the pid
of the child; in the child process fork returns 0. */
#include <sys/wait.h>
#define NULL 0
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(void)
{
    int pidValue = fork();
    if (pidValue > 0) {
/* Parent code here */
        printf("Process[%d]: Parent in execution ... \n", getpid());
        sleep(2);
        if (wait(NULL) > 0) {   /* Child terminating */
            printf("Process[%d]: Parent detects terminating child \n", getpid());
        }
        printf("Process[%d]: Parent terminating ... \n", getpid());
    }
    else {
        if (pidValue == 0) {
/* this is the child's process */
            execve("child1", NULL, NULL);
            exit(0);            /* should never get here, terminate */
        }
        else {
/* should never get here; things such as not
enought mem */
            exit(0);
        }
    }
    return(0);
}