fix cmd: tail

components/finsh/msh_file.c

@@ -612,7 +612,7 @@ static int cmd_tail(int argc, char **argv)
     rt_uint32_t target_line = 0;
     rt_uint32_t current_line = 0;
     rt_uint32_t required_lines = 0;
-    rt_uint32_t after_xxx_line = 0;
+    rt_uint32_t start_line = 0;
 
     if (argc < 2)
     {
@@ -632,7 +632,7 @@ static int cmd_tail(int argc, char **argv)
         }
         else
         {
-            after_xxx_line = atoi(&argv[2][1]); /* eg: +100, to get the 100 */
+            start_line = atoi(&argv[2][1]); /* eg: +100, to get the 100 */
         }
         file_name = argv[3];
     }
@@ -651,6 +651,10 @@ static int cmd_tail(int argc, char **argv)
 
     while ((read(fd, &c, sizeof(char))) > 0)
     {
+        if(total_lines == 0)
+        {
+            total_lines++;
+        }
         if (c == '\n')
         {
             total_lines++;
@@ -659,11 +663,11 @@ static int cmd_tail(int argc, char **argv)
 
     rt_kprintf("\nTotal Number of lines:%d\n", total_lines);
 
-    if (after_xxx_line != 0)
+    if (start_line != 0)
     {
-        if (total_lines > after_xxx_line)
+        if (total_lines >= start_line)
         {
-            required_lines = total_lines - after_xxx_line;
+            required_lines = total_lines - start_line + 1;
         }
         else
         {
@@ -686,13 +690,13 @@ static int cmd_tail(int argc, char **argv)
 
     while ((read(fd, &c, sizeof(char))) > 0)
     {
-        if (c == '\n')
+        if (current_line >= target_line)
         {
-            current_line++;
+            rt_kprintf("%c", c);
         }
-        if (current_line > target_line)
+        if (c == '\n')
         {
-            rt_kprintf("%c", c);
+            current_line++;
         }
     }
     rt_kprintf("\n");