ceb0bbe53d33106b46a2e15b4d14242bf49a3b20
[packages/random.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/base/LICENSE)
6 --
7 -- Maintainer : libraries@haskell.org
8 -- Stability : provisional
9 -- Portability : portable
10 --
11 -- Executing an external command.
12 --
13 -----------------------------------------------------------------------------
14
15 module System.Cmd
16 ( system, -- :: String -> IO ExitCode
17 #ifdef __GLASGOW_HASKELL__
18 rawSystem, -- :: FilePath -> [String] -> IO ExitCode
19 #endif
20 ) where
21
22 import Prelude
23
24 #ifdef __GLASGOW_HASKELL__
25 import System.Process
26 import System.Exit ( ExitCode )
27 import GHC.IOBase ( ioException, IOException(..), IOErrorType(..) )
28 #endif
29
30 #ifdef __HUGS__
31 import Hugs.System
32 #endif
33
34 #ifdef __NHC__
35 import System (system)
36 #endif
37
38 -- ---------------------------------------------------------------------------
39 -- system
40
41 {-|
42 Computation @system cmd@ returns the exit code
43 produced when the operating system processes the command @cmd@.
44
45 This computation may fail with
46
47 * @PermissionDenied@: The process has insufficient privileges to
48 perform the operation.
49
50 * @ResourceExhausted@: Insufficient resources are available to
51 perform the operation.
52
53 * @UnsupportedOperation@: The implementation does not support
54 system calls.
55
56 On Windows, 'system' is implemented using Windows's native system
57 call, which ignores the @SHELL@ environment variable, and always
58 passes the command to the Windows command interpreter (@CMD.EXE@ or
59 @COMMAND.COM@), hence Unixy shell tricks will not work.
60 -}
61 #ifdef __GLASGOW_HASKELL__
62 system :: String -> IO ExitCode
63 system "" = ioException (IOError Nothing InvalidArgument "system" "null command" Nothing)
64 system cmd = do
65 p <- runCommand cmd
66 waitForProcess p
67
68 rawSystem :: String -> [String] -> IO ExitCode
69 rawSystem cmd args = do
70 p <- runProcess cmd args Nothing Nothing Nothing Nothing Nothing
71 waitForProcess p
72 #endif /* __GLASGOW_HASKELL__ */