diff --git a/shell/savePid b/shell/savePid
index d763506..7a5c477 100644
--- a/shell/savePid
+++ b/shell/savePid
@@ -5,7 +5,7 @@ second=5s
 while true
   do
     pid=`findPortPid $1`
-    if [ `echo $pid|wc -l` -eq 0 ]
+    if [ -z $pid ]
     then
       echo "没有找到端口:$1的pid，$second后重试"
       sleep $second