From e56c10c7b60d4e0fac936de1ce473bb9dbd4d9c8 Mon Sep 17 00:00:00 2001
From: DaJiYuQia <88259094+DaJiYuQia@users.noreply.github.com>
Date: Sun, 23 Oct 2022 17:35:40 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E5=88=9D=E5=A7=8B=E5=91=BD?=
 =?UTF-8?q?=E4=BB=A4=E8=A1=8C=E5=88=87=E6=8D=A2=E9=97=AE=E9=A2=98=20(#66)?=
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---
 user/apps/shell/shell.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/user/apps/shell/shell.c b/user/apps/shell/shell.c
index ab9a8fba..687760df 100644
--- a/user/apps/shell/shell.c
+++ b/user/apps/shell/shell.c
@@ -117,7 +117,7 @@ void clear_command(int count, char *buf)
  * @brief 切换命令(写入到缓冲区)
  *
  * @param buf 缓冲区
- * @param type 如果为1,就向下,如果为-1,就向上
+ * @param type 如果为1,就向上,如果为-1,就向下
  */
 void change_command(char *buf, int type)
 {
@@ -126,7 +126,18 @@ void change_command(char *buf, int type)
     if (current_command_index < 0)
         current_command_index++;
     if (current_command_index >= count_history - 1)
-        current_command_index = count_history - 2;
+    {
+        //初始只含一条空历史记录，需单独考虑
+        if(count_history == 1)
+        {
+            //防止出现多条空历史记录
+            if(current_command_index > 1)
+                current_command_index = 1;
+        }
+        else
+            current_command_index = count_history - 2;
+    }
+        
     strcpy(buf, history_commands[current_command_index]);
     printf("%s", buf);
     put_string(" ", COLOR_BLACK, COLOR_WHITE);