parent waits for child to finish first
$ cat -n ostep/code/cpu-api/p2.c
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <unistd.h>
4 #include <sys/wait.h>
5
6 int
7 main(int argc, char *argv[])
8 {
9 printf("hello world (pid:%d)\n", (int) getpid());
10 int rc = fork();
11 if (rc < 0) {
12 // fork failed; exit
13 fprintf(stderr, "fork failed\n");
14 exit(1);
15 } else if (rc == 0) {
16 // child (new process)
17 printf("hello, I am child (pid:%d)\n", (int) getpid());
18 sleep(1);
19 } else {
20 // parent goes down this path (original process)
21 int wc = wait(NULL);
22 printf("hello, I am parent of %d (wc:%d) (pid:%d)\n",
23 rc, wc, (int) getpid());
24 }
25 return 0;
26 }
$ ./p2
hello world (pid:21937)
hello, I am child (pid:21938)
hello, I am parent of 21938 (wc:21938) (pid:21937)
$ ./p2
hello world (pid:21939)
hello, I am child (pid:21940)
hello, I am parent of 21940 (wc:21940) (pid:21939)
$
--> try checking the child exit status
