[project @ 2002-04-24 16:31:37 by simonmar]
[packages/base.git] / System / Cmd.hs
1 -----------------------------------------------------------------------------
2 -- |
3 -- Module : System.Cmd
4 -- Copyright : (c) The University of Glasgow 2001
5 -- License : BSD-style (see the file libraries/core/LICENSE)
6 --
7 -- Maintainer : libraries@haskell.org
8 -- Stability : provisional
9 -- Portability : portable
10 --
11 -- $Id: Cmd.hs,v 1.3 2002/04/24 16:31:45 simonmar Exp $
12 --
13 -- Executing a command.
14 --
15 -----------------------------------------------------------------------------
16
17 module System.Cmd
18 ( system -- :: String -> IO ExitCode
19 ) where
20
21 import Prelude
22
23 import System.Exit
24 import Foreign.C
25
26 #ifdef __GLASGOW_HASKELL__
27 import GHC.IOBase
28 #endif
29
30 -- ---------------------------------------------------------------------------
31 -- system
32
33 -- Computation `system cmd' returns the exit code
34 -- produced when the operating system processes the command `cmd'.
35
36 -- This computation may fail with
37 -- PermissionDenied
38 -- The process has insufficient privileges to perform the operation.
39 -- ResourceExhausted
40 -- Insufficient resources are available to perform the operation.
41 -- UnsupportedOperation
42 -- The implementation does not support system calls.
43
44 system :: String -> IO ExitCode
45 system "" = ioException (IOError Nothing InvalidArgument "system" "null command" Nothing)
46 system cmd =
47 withCString cmd $ \s -> do
48 status <- throwErrnoIfMinus1 "system" (primSystem s)
49 case status of
50 0 -> return ExitSuccess
51 n -> return (ExitFailure n)
52
53 foreign import ccall unsafe "systemCmd" primSystem :: CString -> IO Int