diff --git a/README.md b/README.md
index 78fe9b7..612596c 100644
--- a/README.md
+++ b/README.md
@@ -123,6 +123,8 @@ python run.py -c /path/to/config.json
 	* 如果想匹配`10.00.xxxx`应该写成`"10\\.00\\..*"`(`"\\"`json转义成`\`)
 * 字符串`"default"`(或者无此项): 系统访问外网默认IP
 * 字符串`"public"`: 使用公网ip(使用公网API查询)
+* 字符串`"cmd:xxxx"`: 执行命令`xxxx`的stdout输出结果作为目标IP
+* 字符串`"shell:xxx"`: 使用系统shell运行`xxx`,并把结果stdout作为目标IP
 * `false`: 强制禁止更新ipv4或ipv6的DNS解析
 
 #### 配置示例
diff --git a/dns/dnspod.py b/dns/dnspod.py
index c4fb54e..1156405 100644
--- a/dns/dnspod.py
+++ b/dns/dnspod.py
@@ -69,6 +69,7 @@ def get_domain_info(domain):
     切割域名获取主域名和对应ID
     """
     domain_split = domain.split('.')
+    sub = '@' # root domain根域名https://github.com/NewFuture/DDNS/issues/9
     if len(domain_split) == 3:  # 长度为3
         sub, main = domain_split[0], domain_split[1] + '.' + domain_split[2]
         did = get_domain_id(main)
@@ -82,9 +83,7 @@ def get_domain_info(domain):
                 break
         else:
             warning('domain_id: %s, sub: %s', did, sub)
-            return None, None
-        if not sub:  # root domain根域名https://github.com/NewFuture/DDNS/issues/9
-            sub = '@'
+            return None, None 
     info('domain_id: %s, sub: %s', did, sub)
     return did, sub
 
diff --git a/dns/dnspod_com.py b/dns/dnspod_com.py
index 8398cd9..0e037de 100644
--- a/dns/dnspod_com.py
+++ b/dns/dnspod_com.py
@@ -73,6 +73,7 @@ def get_domain_info(domain):
     切割域名获取主域名和对应ID
     """
     domain_split = domain.split('.')
+    sub = '@' # root domain根域名https://github.com/NewFuture/DDNS/issues/9
     if len(domain_split) == 3:  # 长度为3
         sub, main = domain_split[0], domain_split[1] + '.' + domain_split[2]
         did = get_domain_id(main)
@@ -87,8 +88,6 @@ def get_domain_info(domain):
         else:
             warning('domain_id: %s, sub: %s', did, sub)
             return None, None
-        if not sub:  # root domain根域名https://github.com/NewFuture/DDNS/issues/9
-            sub = '@'
     return did, sub
 
 
diff --git a/run.py b/run.py
index e0f8e9c..93b6d54 100755
--- a/run.py
+++ b/run.py
@@ -12,6 +12,7 @@ from time import ctime
 from os import path, environ, stat, name as os_name
 from tempfile import gettempdir
 from logging import DEBUG, basicConfig, info, warning, error
+from subprocess import check_output
 
 import sys
 
@@ -84,6 +85,10 @@ def get_ip(ip_type):
         return False
     elif str(index).isdigit():  # local eth
         value = getattr(ip, "local_v" + ip_type)(index)
+    elif index.startswith('cmd:'): # cmd
+        value = check_output(index[4:]).strip()
+    elif index.startswith('shell:'): # shell
+        value = check_output(index[6:], shell=True).strip()
     elif any((c in index) for c in '*.:'):  # regex
         value = getattr(ip, "regex_v" + ip_type)(index)
     else: