linux fork() C example - parent process starts a child process that sleeps for 3 seconds and either waits or terminates it.

forkex1.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/wait.h>
#include <unistd.h>

int main()
{
	int pid;
	int status;
	if ((pid = fork()) > 0)
	{
		puts("Parent waiting...");
		srand(time(NULL));
		if (rand() % 2)
		{
			puts("sending signal SIGKILL");
			kill(pid, SIGKILL);
		}

		wait4(pid, &status, 0, NULL);
		puts("Parent stopped waiting");
		if (WIFEXITED(status))
			puts("Child exited successfully");
		if (WIFSIGNALED(status))
			puts("Child terminated by a signal");
	}
	else
	{
		if (pid == 0)
		{
			/*Child*/
			char *argv[] = { "/bin/sleep", "3", NULL};
			execve("/bin/sleep", argv, NULL);
		}
		else
		{
			fprintf(stderr, "fork() failure\n");
		}
	}
	return 0;
}