[project @ 2004-05-06 08:44:52 by simonmar]

[ghc-base.git] / System / Cmd.hs

diff --git a/System/Cmd.hs b/System/Cmd.hs
index 0be8008..cb8d2d9 100644 (file)
--- a/System/Cmd.hs
+++ b/System/Cmd.hs
@@ -8,37 +8,59 @@
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- Executing a command.
+-- Executing an external command.
 --
 -----------------------------------------------------------------------------
 
 module System.Cmd
-    ( system        -- :: String -> IO ExitCode
+    ( system,        -- :: String -> IO ExitCode
+#ifdef __GLASGOW_HASKELL__
+      rawSystem,     -- :: FilePath -> [String] -> IO ExitCode
+#endif
     ) where
 
 import Prelude
 
-import System.Exit
-import Foreign.C
-
 #ifdef __GLASGOW_HASKELL__
+import Foreign
+import Foreign.C
+import System.Exit
 import GHC.IOBase
+#include "config.h"
+#endif
+
+#ifdef __HUGS__
+import Hugs.System
+#endif
+
+#ifdef __NHC__
+import System (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.
 
--- 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.
+   * @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.
+-}
+#ifdef __GLASGOW_HASKELL__
 system :: String -> IO ExitCode
 system "" = ioException (IOError Nothing InvalidArgument "system" "null command" Nothing)
 system cmd =
@@ -49,3 +71,10 @@ system cmd =
         n  -> return (ExitFailure n)
 
 foreign import ccall unsafe "systemCmd" primSystem :: CString -> IO Int
+#endif  /* __GLASGOW_HASKELL__ */
+
+-- ---------------------------------------------------------------------------
+-- rawSystem
+
+-- rawSystem is in a separate file, so we can #include it various places.
+#include "RawSystem.hs-inc"