1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <sys/wait.h>
   5 #include <sys/types.h>
   6 
   7 int main(int argc, char *argv[])
   8 {
   9     pid_t pid;
  10     
  11     if((pid = fork()) == 0) 
  12     { // child
  13         printf("sleeping...\n");
  14         sleep(3);
  15         printf("waking ... and exiting\n");
  16     } 
  17     else if (pid > 0) 
  18     { // parent
  19         printf("waiting for child\n");
  20         wait(NULL);
  21         printf("child woke up\n");
  22     }
  23     exit(0);
  24 }