diff --git a/xcmd/xcmd.c b/xcmd/xcmd.c
index 6d2a551..37869f5 100755
--- a/xcmd/xcmd.c
+++ b/xcmd/xcmd.c
@@ -1,6 +1,7 @@
 #include "xcmd.h"
 #include "malloc.h"
 
+
 #define CMD_IS_ENDLINE(c) ((c == '\n') || (c == '\r'))
 #define CMD_IS_PRINT(c) ((c >= 32) && (c <= 126))
 
@@ -128,13 +129,13 @@ static uint32_t xcmd_bytes_encode(xcmder_t * cmder, uint8_t byte)
 static void xcmd_display_update(xcmder_t *cmder)
 {
 	char *line = xcmd_display_get(cmder);
-    xcmd_print_str(cmder, "\r->");
-    xcmd_print_str(cmder, line);
-    xcmd_print_str(cmder, "\r->");
+    xcmd_print(cmder, "\r->");
+    xcmd_print(cmder, line);
+    xcmd_print(cmder, "\r->");
     /* move cursor */
     for(uint16_t i = 0; i<cmder->parser.cursor; i++)
     {
-        xcmd_print_str(cmder, "\x1B\x5B\x43");
+        xcmd_print(cmder, "\x1B\x5B\x43");
     }
 }
 
@@ -157,12 +158,12 @@ static char* xcmd_line_end(xcmder_t *cmder)
         }
         cmder->parser.byte_num = 0;
         cmder->parser.cursor = 0;
-        xcmd_print_str(cmder, "\r\n");
+        xcmd_print(cmder, "\r\n");
         xcmd_history_reset(cmder);
 	}
 	else
 	{
-	    xcmd_print_str(cmder, "\r\n->");
+	    xcmd_print(cmder, "\r\n->");
 	}
 	return ret;
 }
@@ -191,11 +192,26 @@ static char* xcmd_parser(xcmder_t * cmder, uint8_t byte)
 }
 
 void xcmd_print_str(xcmder_t * cmder, char* str)
-{
+{    
 	while(*str)
 	{
 		cmder->io.put_c(*str++);
 	}
+    return;
+}
+
+void xcmd_print(xcmder_t * cmder, const char *fmt, ...)
+{
+    char  ucstring[256] = {0};
+    unsigned short wdatalen;
+    va_list arg;
+
+    va_start(arg, fmt);
+    wdatalen = vsprintf(ucstring, fmt, arg);
+    va_end(arg);
+
+    xcmd_print_str(cmder, ucstring);
+    return;
 }
 
 char* xcmd_display_get(xcmder_t *cmder)
@@ -210,12 +226,12 @@ void xcmd_display_clear(xcmder_t *cmder)
     uint16_t len = strlen(line);
 	if(len)
 	{
-	    xcmd_print_str(cmder, "\r->");
+	    xcmd_print(cmder, "\r->");
 	    for(uint16_t i=0; i<len; i++)
 	    {
 	        cmder->io.put_c(' ');
 	    }
-	    xcmd_print_str(cmder, "\r->");
+	    xcmd_print(cmder, "\r->");
         cmder->parser.byte_num = 0;
         cmder->parser.cursor = 0;
         line[0] = '\0';
diff --git a/xcmd/xcmd.h b/xcmd/xcmd.h
index 746f7cb..a6b9d73 100755
--- a/xcmd/xcmd.h
+++ b/xcmd/xcmd.h
@@ -7,6 +7,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <math.h>
+#include <stdarg.h>
 
 typedef void(*cmd_func_t)(int argv, char* argc[]);
 typedef int(*cmd_key_func_t)(void *data);
@@ -190,7 +191,8 @@ uint8_t xcmd_exec(xcmder_t *cmder, char *str);
  * @param {char*} str
  * @return 无
  */
-void xcmd_print_str(xcmder_t * cmder, char* str);
+void xcmd_print(xcmder_t * cmder, const char *fmt, ...);
+
 
 /**
  * @description: 向显示器插入一个字符
diff --git a/xcmd/xcmd_default_cmds.c b/xcmd/xcmd_default_cmds.c
index bc209c2..f773e10 100755
--- a/xcmd/xcmd_default_cmds.c
+++ b/xcmd/xcmd_default_cmds.c
@@ -5,7 +5,7 @@ static xcmder_t *g_cmder = NULL;
 
 static void cmd_clear(int argc, char* argv[])
 {
-    printf("\033c");
+    xcmd_print(g_cmder, "\033c");
 }
 
 static void cmd_help(int argc, char* argv[])
@@ -13,7 +13,7 @@ static void cmd_help(int argc, char* argv[])
     xcmd_t *p = g_cmder->cmd_list.next;
     while(p)
     {
-        printf("%-20s %s\r\n",p->name, p->help);
+        xcmd_print(g_cmder, "%-20s %s\r\n",p->name, p->help);
         p = p->next;
     }
 }
@@ -30,7 +30,7 @@ static void cmd_logo(int argc, char* argv[])
 ( \\/ )/ __)(  \\/  )(  _ \\ \n\
  )  (( (__  )    (  )(_) )\n\
 (_/\\_)\\___)(_/\\/\\_)(____/\n ";
-    printf("%s", log);
+    xcmd_print(g_cmder, "%s", log);
 }
 
 static xcmd_t cmds[] = 
diff --git a/xcmd/xcmd_default_keys.c b/xcmd/xcmd_default_keys.c
index 23d54c1..cef3e82 100755
--- a/xcmd/xcmd_default_keys.c
+++ b/xcmd/xcmd_default_keys.c
@@ -24,7 +24,7 @@ static int xcmd_cursor_left(void *pv)
 	if(cmder->parser.cursor > 0)
 	{
 		cmder->parser.cursor--;
-        xcmd_print_str(cmder, STR_LEFT);
+        xcmd_print(cmder, STR_LEFT);
 	}
     return 0;
 }
@@ -35,7 +35,7 @@ static int xcmd_cursor_right(void *pv)
 	if(cmder->parser.cursor < cmder->parser.byte_num)
 	{
 		cmder->parser.cursor++;
-        xcmd_print_str(cmder, STR_RIGHT);
+        xcmd_print(cmder, STR_RIGHT);
 	}
     return 0;
 }
@@ -52,7 +52,7 @@ static int xcmd_history_dw(void *pv)
         if (len)
         {
             strncpy(display_line, line, cmder->parser.line_len);
-            xcmd_print_str(cmder, line);
+            xcmd_print(cmder, line);
             cmder->parser.byte_num = len;
             cmder->parser.cursor = len;
         }
@@ -76,7 +76,7 @@ static int xcmd_history_up(void *pv)
         if (len)
         {
             strncpy(display_line, line, cmder->parser.line_len);
-            xcmd_print_str(cmder, line);
+            xcmd_print(cmder, line);
             cmder->parser.byte_num = len;
             cmder->parser.cursor = len;
         }
@@ -84,13 +84,31 @@ static int xcmd_history_up(void *pv)
     return 0;
 }
 
+static int xcmd_auto_completion(void *pv)
+{
+    
+    xcmder_t *cmder = (xcmder_t*)pv;
+    char *pdat = xcmd_display_get(cmder);
+
+    xcmd_t *p = cmder->cmd_list.next;
+    while(p)
+    {
+        printf("%-20s %s\r\n",p->name, p->help);
+        p = p->next;
+    }
+    return 0;
+}
+
+
 static xcmd_key_t default_keys[] = 
 {
-    {L_DELETE, xcmd_del_char,  NULL},
-    {LEFT, xcmd_cursor_left, NULL},
-    {RIGHT, xcmd_cursor_right, NULL},
-    {DW, xcmd_history_dw, NULL},
-    {UP, xcmd_history_up, NULL},
+    {BACKSPACE,     xcmd_del_char,          NULL},
+    {L_DELETE,      xcmd_del_char,          NULL},
+    {LEFT,          xcmd_cursor_left,       NULL},
+    {RIGHT,         xcmd_cursor_right,      NULL},
+    {DW,            xcmd_history_dw,        NULL},
+    {UP,            xcmd_history_up,        NULL},
+    {TAB,           xcmd_auto_completion,   NULL},
 };
 
 void default_keys_init(xcmder_t *cmder)