Added Process exercise's chapter

ex19.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int main(void) {
+  pid_t parent_pid = getpid();
+  pid_t pid = fork();
+
+  if (pid > 0) {
+    printf("PARENT PID = %d, CHILD PID = %d\n", parent_pid, pid);
+    sleep(10);
+    wait(NULL);
+  }
+
+  return EXIT_SUCCESS;
+}