diff --git a/is_master.go b/is_master.go
index ffb4b35..3bdafad 100644
--- a/is_master.go
+++ b/is_master.go
@@ -16,6 +16,7 @@ var (
   IP      = flag.String("ip", "", "")
   FILE    = flag.String("file", "", "")
   COMMAND = flag.String("command", "", "command to execute")
+  NOT     = flag.Bool("not", false, "execute the command if the ip or the file isn't present")
 )
 
 // Critical print a message and exit with code 2
@@ -86,15 +87,23 @@ func ipExist(ip string) bool {
 }
 
 func main() {
-  var isMaster bool
+  var execute bool
 
   if *FILE != "" {
-    isMaster = fileExist(*FILE)
+    execute = fileExist(*FILE)
   } else {
-    isMaster = ipExist(*IP)
+    execute = ipExist(*IP)
   }
 
-  if isMaster == false {
+  if *NOT {
+    if execute {
+      execute = false
+    } else {
+      execute = true
+    }
+  }
+
+  if execute {
     Ok("I have nothing to do, i going to sleep")
   }