--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/uprogs/init.c	Sun Oct 22 18:25:39 2017 +0900
@@ -0,0 +1,37 @@
+// init: The initial user-level program
+
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fcntl.h"
+
+char *argv[] = { "sh", 0 };
+
+int
+main(void)
+{
+  int pid, wpid;
+
+  if(open("console", O_RDWR) < 0){
+    mknod("console", 1, 1);
+    open("console", O_RDWR);
+  }
+  dup(0);  // stdout
+  dup(0);  // stderr
+
+  for(;;){
+    printf(1, "init: starting sh\n");
+    pid = fork();
+    if(pid < 0){
+      printf(1, "init: fork failed\n");
+      exit();
+    }
+    if(pid == 0){
+      exec("sh", argv);
+      printf(1, "init: exec sh failed\n");
+      exit();
+    }
+    while((wpid=wait()) >= 0 && wpid != pid)
+      printf(1, "zombie!\n");
+  }
+}