shell can launch another user processgit add .git add .!

kernel/scheduler.c

@@ -186,4 +186,13 @@ void wake(process_t* task) {
     if (task->state == STATE_SLEEPING || task->state == STATE_BLOCKED) {
         task->state = STATE_READY;
     }
+}
+
+process_t* get_task_by_pid(uint32_t pid) {
+    process_t* cur = process_table;
+    while (cur) {
+        if (cur->pid == pid) break;
+        cur = cur->sched_next;
+    }
+    return cur;
 }