-- |
-- Module : System.Cmd
-- Copyright : (c) The University of Glasgow 2001
--- License : BSD-style (see the file libraries/core/LICENSE)
+-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
-- Portability : portable
--
--- Executing a command.
+-- Executing an external command.
--
-----------------------------------------------------------------------------
module System.Cmd
- ( system -- :: String -> IO ExitCode
+ ( system, -- :: String -> IO ExitCode
+#ifndef __HUGS__
+ rawSystem, -- :: String -> IO ExitCode
+#endif
) where
import Prelude
import System.Exit
+#ifndef __HUGS__
import Foreign.C
+#endif
#ifdef __GLASGOW_HASKELL__
import GHC.IOBase
#endif
+#ifdef __HUGS__
+import Hugs.System
+#endif
+
-- ---------------------------------------------------------------------------
-- system
--- Computation `system cmd' returns the exit code
--- produced when the operating system processes the command `cmd'.
+{-|
+Computation @system cmd@ returns the exit code
+produced when the operating system processes the command @cmd@.
--- This computation may fail with
--- PermissionDenied
--- The process has insufficient privileges to perform the operation.
--- ResourceExhausted
--- Insufficient resources are available to perform the operation.
--- UnsupportedOperation
--- The implementation does not support system calls.
+This computation may fail with
+ * @PermissionDenied@: The process has insufficient privileges to
+ perform the operation.
+
+ * @ResourceExhausted@: Insufficient resources are available to
+ perform the operation.
+
+ * @UnsupportedOperation@: The implementation does not support
+ system calls.
+
+On Windows, 'system' is implemented using Windows's native system
+call, which ignores the @SHELL@ environment variable, and always
+passes the command to the Windows command interpreter (@CMD.EXE@ or
+@COMMAND.COM@), hence Unixy shell tricks will not work.
+-}
+#ifndef __HUGS__
system :: String -> IO ExitCode
system "" = ioException (IOError Nothing InvalidArgument "system" "null command" Nothing)
system cmd =
n -> return (ExitFailure n)
foreign import ccall unsafe "systemCmd" primSystem :: CString -> IO Int
+
+{- |
+The same as 'system', but bypasses the shell. Will behave more portably between
+systems, because there is no interpretation of shell metasyntax.
+-}
+
+rawSystem :: String -> IO ExitCode
+rawSystem "" = ioException (IOError Nothing InvalidArgument "rawSystem" "null command" Nothing)
+rawSystem cmd =
+ withCString cmd $ \s -> do
+ status <- throwErrnoIfMinus1 "rawSystem" (primRawSystem s)
+ case status of
+ 0 -> return ExitSuccess
+ n -> return (ExitFailure n)
+
+foreign import ccall unsafe "rawSystemCmd" primRawSystem :: CString -> IO Int
+
+#endif /* __HUGS__ */