diff --git a/Test/Hspec/Server/Command.hs b/Test/Hspec/Server/Command.hs
--- a/Test/Hspec/Server/Command.hs
+++ b/Test/Hspec/Server/Command.hs
@@ -1,6 +1,7 @@
 module Test.Hspec.Server.Command where
 
 import System.Exit
+import Control.Monad
 import Control.Monad.IO.Class
 import Data.Monoid
 import Text.Regex.Posix
@@ -10,7 +11,9 @@
 package :: ServerType dat => String -> ServerExample dat ServerStatus
 package pkg = do
   dat <- getServerData
-  (_,out,_) <- liftIO $ cmd dat "dpkg" ["-l",pkg] []
+  c@(code,out,_) <- liftIO $ cmd dat "dpkg" ["-l",pkg] []
+  when (code /= ExitSuccess) $ do
+    error $ "pacakge error:" ++ show c
   if or (map (\v -> v  =~ ("^ii +" <> pkg <> " ")) (lines out))
     then return Installed
     else return None
@@ -26,7 +29,9 @@
 service :: ServerType dat => String -> ServerExample dat ServerStatus
 service s = do
   dat <- getServerData
-  (_,out,_) <- liftIO $ cmd dat ("/etc/init.d/"++s) ["status"] []
+  c@(code,out,_) <- liftIO $ cmd dat ("/etc/init.d/"++s) ["status"] []
+  when (code /= ExitSuccess) $ do
+    error $ "service error:" ++ show c
   if or (map (\v ->
                (v  =~ ("is running" :: String)) ||
                (v  =~ ("start/running" :: String))
@@ -37,7 +42,9 @@
 port :: ServerType dat => Int -> ServerExample dat ServerStatus
 port p = do
   dat <- getServerData
-  (_,out,_) <- liftIO $ cmd dat "netstat" ["-tanp"] []
+  c@(code,out,_) <- liftIO $ cmd dat "netstat" ["-tanp"] []
+  when (code /= ExitSuccess) $ do
+    error $ "port error:" ++ show c
   if or (map (\v ->
                (v  =~ ("^tcp[ 6] +[0-9]+ +[0-9]+ :::" <> show p <> " +[^ ]+ +LISTEN")) ||
                (v  =~ ("^tcp[ 6] +[0-9]+ +[0-9]+ [0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+:" <> show p <> " +[^ ]+ +LISTEN"))
diff --git a/Test/Hspec/Server/Type.hs b/Test/Hspec/Server/Type.hs
--- a/Test/Hspec/Server/Type.hs
+++ b/Test/Hspec/Server/Type.hs
@@ -6,6 +6,7 @@
 import Control.Monad.Trans.Writer
 import qualified Test.Hspec.Core.Spec as Hspec
 
+import Control.Monad
 import Data.Monoid
 import Data.List
 import Data.Maybe
@@ -122,16 +123,23 @@
 
 detectOS :: ServerType dat => dat -> IO (Maybe ServerOS)
 detectOS dat = do
-  (_,out,_) <- cmd dat "sh" ["-c","echo $OSTYPE"] []
-  case (head (lines out)) of
-    "linux-gnu" -> detectLinux dat
-    'd':'a':'r':'w':'i':'n':o -> return $ Just $ MacOS o
-    "msys" -> return $ Just $ Windows "msys"
-    "cygwin" -> return $ Just $ Windows "cygwin"
-    "win32" -> return $ Just $ Windows "win32"
-    "win64" -> return $ Just $ Windows "win64"
-    'f':'r':'e':'e':'b':'s':'d':o -> return $ Just $ FreeBSD o
-    o -> return $ Just $ OtherOS o
+  v@(code,out,_) <- cmd dat "sh" ["-c","echo $OSTYPE"] []
+  when (code /= ExitSuccess) $ do
+    error $ "detectOS's error;" ++ show v
+  case listToMaybe (lines out) of
+    Just str -> checkEnv str
+    Nothing -> return Nothing
+  where
+    checkEnv str =   
+      case str of
+        "linux-gnu" -> detectLinux dat
+        'd':'a':'r':'w':'i':'n':o -> return $ Just $ MacOS o
+        "msys" -> return $ Just $ Windows "msys"
+        "cygwin" -> return $ Just $ Windows "cygwin"
+        "win32" -> return $ Just $ Windows "win32"
+        "win64" -> return $ Just $ Windows "win64"
+        'f':'r':'e':'e':'b':'s':'d':o -> return $ Just $ FreeBSD o
+        o -> return $ Just $ OtherOS o
 
 detectLinux :: ServerType dat => dat -> IO (Maybe ServerOS)
 detectLinux dat = do
diff --git a/hspec-server.cabal b/hspec-server.cabal
--- a/hspec-server.cabal
+++ b/hspec-server.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                hspec-server
-version:             0.2.1
+version:             0.2.2
 synopsis:            Test Framework for Server's status
 description:         Hspec-Server is test framework for checking server's status.
                      It is inspired by the Ruby library ServerSpec.