System.Process.Typed.Internal

This module is internal and its contents may change without a warning or announcement. It is not subject to the PVP.

Documentation

data ProcessConfig stdin stdout stderr

An abstract configuration for a process, which can then be launched into an actual running Process. Takes three type parameters, providing the types of standard input, standard output, and standard error, respectively.

There are three ways to construct a value of this type:

• With the proc smart constructor, which takes a command name and a list of arguments.
• With the shell smart constructor, which takes a shell string
• With the IsString instance via OverloadedStrings. If you provide it a string with no spaces (e.g., "date"), it will treat it as a raw command with no arguments (e.g., proc "date" []). If it has spaces, it will use shell.

In all cases, the default for all three streams is to inherit the streams from the parent process. For other settings, see the setters below for default values.

Once you have a ProcessConfig you can launch a process from it using the functions in the section Launch a process.

Since: 0.1.0.0

Constructors

ProcessConfig

Fields

• pcCmdSpec :: !CmdSpec
• pcStdin :: !(StreamSpec 'STInput stdin)
• pcStdout :: !(StreamSpec 'STOutput stdout)
• pcStderr :: !(StreamSpec 'STOutput stderr)
• pcWorkingDir :: !(Maybe FilePath)
• pcEnv :: !(Maybe [(String, String)])
• pcCloseFds :: !Bool
• pcCreateGroup :: !Bool
• pcDelegateCtlc :: !Bool
• pcDetachConsole :: !Bool
• pcCreateNewConsole :: !Bool
• pcNewSession :: !Bool
• pcChildGroup :: !(Maybe GroupID)
• pcChildUser :: !(Maybe UserID)

Instances

(stdin ~ (), stdout ~ (), stderr ~ ()) => IsString (ProcessConfig stdin stdout stderr)

Defined in System.Process.Typed.Internal

Methods

fromString :: String -> ProcessConfig stdin stdout stderr

Show (ProcessConfig stdin stdout stderr)

Defined in System.Process.Typed.Internal

Methods

showsPrec :: Int -> ProcessConfig stdin stdout stderr -> ShowS

show :: ProcessConfig stdin stdout stderr -> String

showList :: [ProcessConfig stdin stdout stderr] -> ShowS

data StreamType

Whether a stream is an input stream or output stream. Note that this is from the perspective of the child process, so that a child's standard input stream is an STInput, even though the parent process will be writing to it.

Since: 0.1.0.0

Constructors

STInput

STOutput

data StreamSpec (streamType :: StreamType) a

A specification for how to create one of the three standard child streams, stdin, stdout and stderr. A StreamSpec can be thought of as containing

1. A type safe version of StdStream from System.Process. This determines whether the stream should be inherited from the parent process, piped to or from a Handle, etc.
2. A means of accessing the stream as a value of type a
3. A cleanup action which will be run on the stream once the process terminates

To create a StreamSpec see the section Stream specs.

Since: 0.1.0.0

Constructors

StreamSpec

Fields

• ssStream :: !(forall b. (StdStream -> IO b) -> IO b)
• ssCreate :: !(ProcessConfig () () () -> Maybe Handle -> Cleanup a)

Instances

Functor (StreamSpec streamType)

Defined in System.Process.Typed.Internal

Methods

fmap :: (a -> b) -> StreamSpec streamType a -> StreamSpec streamType b

(<$) :: a -> StreamSpec streamType b -> StreamSpec streamType a

(streamType ~ 'STInput, res ~ ()) => IsString (StreamSpec streamType res)

This instance uses byteStringInput to convert a raw string into a stream of input for a child process.

Since: 0.1.0.0

Defined in System.Process.Typed.Internal

Methods

fromString :: String -> StreamSpec streamType res

newtype Cleanup a

Internal type, to make for easier composition of cleanup actions.

Since: 0.1.0.0

Constructors

Cleanup

Fields

• runCleanup :: IO (a, IO ())

Instances

Applicative Cleanup

Defined in System.Process.Typed.Internal

Methods

pure :: a -> Cleanup a

(<*>) :: Cleanup (a -> b) -> Cleanup a -> Cleanup b

liftA2 :: (a -> b -> c) -> Cleanup a -> Cleanup b -> Cleanup c

(*>) :: Cleanup a -> Cleanup b -> Cleanup b

(<*) :: Cleanup a -> Cleanup b -> Cleanup a

Functor Cleanup

Defined in System.Process.Typed.Internal

Methods

fmap :: (a -> b) -> Cleanup a -> Cleanup b

(<$) :: a -> Cleanup b -> Cleanup a

defaultProcessConfig :: ProcessConfig () () ()

Internal helper

proc :: FilePath -> [String] -> ProcessConfig () () ()

Create a ProcessConfig from the given command and arguments.

Since: 0.1.0.0

setProc :: FilePath -> [String] -> ProcessConfig stdin stdout stderr -> ProcessConfig stdin stdout stderr

Internal helper

shell :: String -> ProcessConfig () () ()

Create a ProcessConfig from the given shell command.

Since: 0.1.0.0

setShell :: String -> ProcessConfig stdin stdout stderr -> ProcessConfig stdin stdout stderr

Internal helper

setStdin

Arguments

:: StreamSpec 'STInput stdin

-> ProcessConfig stdin0 stdout stderr

-> ProcessConfig stdin stdout stderr

Set the child's standard input stream to the given StreamSpec.

Default: inherit

Since: 0.1.0.0

setStdout

Arguments

:: StreamSpec 'STOutput stdout

-> ProcessConfig stdin stdout0 stderr

-> ProcessConfig stdin stdout stderr

Set the child's standard output stream to the given StreamSpec.

Default: inherit

Since: 0.1.0.0

setStderr

Arguments

:: StreamSpec 'STOutput stderr

-> ProcessConfig stdin stdout stderr0

-> ProcessConfig stdin stdout stderr

Set the child's standard error stream to the given StreamSpec.

Default: inherit

Since: 0.1.0.0

setWorkingDir

Arguments

:: FilePath

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Set the working directory of the child process.

Default: current process's working directory.

Since: 0.1.0.0

setWorkingDirInherit

Arguments

:: ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Inherit the working directory from the parent process.

Since: 0.2.2.0

setEnv

Arguments

:: [(String, String)]

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Set the environment variables of the child process.

Default: current process's environment.

Since: 0.1.0.0

setEnvInherit

Arguments

:: ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Inherit the environment variables from the parent process.

Since: 0.2.2.0

setCloseFds

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Should we close all file descriptors besides stdin, stdout, and stderr? See close_fds for more information.

Default: False

Since: 0.1.0.0

setCreateGroup

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Should we create a new process group?

Default: False

Since: 0.1.0.0

setDelegateCtlc

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Delegate handling of Ctrl-C to the child. For more information, see delegate_ctlc.

Default: False

Since: 0.1.0.0

setDetachConsole

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Detach console on Windows, see detach_console.

Default: False

Since: 0.1.0.0

setCreateNewConsole

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Create new console on Windows, see create_new_console.

Default: False

Since: 0.1.0.0

setNewSession

Arguments

:: Bool

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Set a new session with the POSIX setsid syscall, does nothing on non-POSIX. See new_session.

Default: False

Since: 0.1.0.0

setChildGroup

Arguments

:: GroupID

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Set the child process's group ID with the POSIX setgid syscall, does nothing on non-POSIX. See child_group.

Default: False

Since: 0.1.0.0

setChildGroupInherit

Arguments

:: ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Inherit the group from the parent process.

Since: 0.2.2.0

setChildUser

Arguments

:: UserID

-> ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Set the child process's user ID with the POSIX setuid syscall, does nothing on non-POSIX. See child_user.

Default: False

Since: 0.1.0.0

setChildUserInherit

Arguments

:: ProcessConfig stdin stdout stderr

-> ProcessConfig stdin stdout stderr

Inherit the user from the parent process.

Since: 0.2.2.0

mkStreamSpec

Arguments

:: StdStream

-> (ProcessConfig () () () -> Maybe Handle -> IO (a, IO ()))

-> StreamSpec streamType a

Create a new StreamSpec from the given StdStream and a helper function. This function:

• Takes as input the raw Maybe Handle returned by the createProcess function. The handle will be Just Handle if the StdStream argument is CreatePipe and Nothing otherwise. See createProcess for more details.
• Returns the actual stream value a, as well as a cleanup function to be run when calling stopProcess.

If making a StreamSpec with CreatePipe, prefer mkPipeStreamSpec, which encodes the invariant that a Handle is created.

Since: 0.1.0.0

mkPipeStreamSpec

Arguments

:: (ProcessConfig () () () -> Handle -> IO (a, IO ()))

-> StreamSpec streamType a

Create a new CreatePipe StreamSpec from the given function. This function:

• Takes as input the Handle returned by the createProcess function. See createProcess for more details.
• Returns the actual stream value a, as well as a cleanup function to be run when calling stopProcess.

Since: 0.2.10.0

mkManagedStreamSpec

Arguments

:: (forall b. (StdStream -> IO b) -> IO b)

-> (ProcessConfig () () () -> Maybe Handle -> IO (a, IO ()))

-> StreamSpec streamType a

Create a new StreamSpec from a function that accepts a StdStream and a helper function. This function is the same as the helper in mkStreamSpec

inherit :: StreamSpec anyStreamType ()

A stream spec which simply inherits the stream of the parent process.

Since: 0.1.0.0

nullStream :: StreamSpec anyStreamType ()

A stream spec which is empty when used for for input and discards output. Note this requires your platform's null device to be available when the process is started.

Since: 0.2.5.0

closed :: StreamSpec anyStreamType ()

A stream spec which will close the stream for the child process. You usually do not want to use this, as it will leave the corresponding file descriptor unassigned and hence available for re-use in the child process. Prefer nullStream unless you're certain you want this behavior.

Since: 0.1.0.0

byteStringInput :: ByteString -> StreamSpec 'STInput ()

An input stream spec which sets the input to the given ByteString. A separate thread will be forked to write the contents to the child process.

Since: 0.1.0.0

byteStringOutput :: StreamSpec 'STOutput (STM ByteString)

Capture the output of a process in a ByteString.

This function will fork a separate thread to consume all input from the process, and will only make the results available when the underlying Handle is closed. As this is provided as an STM action, you can either check if the result is available, or block until it's ready.

In the event of any exception occurring when reading from the Handle, the STM action will throw a ByteStringOutputException.

Since: 0.1.0.0

byteStringFromHandle

Arguments

:: ProcessConfig () () ()

-> Handle

reader handle

-> IO (STM ByteString, IO ())

Helper function (not exposed) for both byteStringOutput and withProcessInterleave. This will consume all of the output from the given Handle in a separate thread and provide access to the resulting ByteString via STM. Second action will close the reader handle.

createPipe :: StreamSpec anyStreamType Handle

Create a new pipe between this process and the child, and return a Handle to communicate with the child.

Since: 0.1.0.0

useHandleOpen :: Handle -> StreamSpec anyStreamType ()

Use the provided Handle for the child process, and when the process exits, do not close it. This is useful if, for example, you want to have multiple processes write to the same log file sequentially.

Since: 0.1.0.0

useHandleClose :: Handle -> StreamSpec anyStreamType ()

Use the provided Handle for the child process, and when the process exits, close it. If you have no reason to keep the Handle open, you should use this over useHandleOpen.

Since: 0.1.0.0

data ExitCodeException

Exception thrown by checkExitCode in the event of a non-success exit code. Note that checkExitCode is called by other functions as well, like runProcess_ or readProcess_.

Note that several functions that throw an ExitCodeException intentionally do not populate eceStdout or eceStderr. This prevents unbounded memory usage for large stdout and stderrs.

Functions which do include eceStdout or eceStderr (like readProcess_) state so in their documentation.

Since: 0.1.0.0

Constructors

ExitCodeException

Fields

• eceExitCode :: ExitCode
• eceProcessConfig :: ProcessConfig () () ()
• eceStdout :: ByteString
• eceStderr :: ByteString

Instances

Exception ExitCodeException

Defined in System.Process.Typed.Internal

Methods

toException :: ExitCodeException -> SomeException

fromException :: SomeException -> Maybe ExitCodeException

displayException :: ExitCodeException -> String

Show ExitCodeException

Defined in System.Process.Typed.Internal

Methods

showsPrec :: Int -> ExitCodeException -> ShowS

show :: ExitCodeException -> String

showList :: [ExitCodeException] -> ShowS

data ByteStringOutputException

Wrapper for when an exception is thrown when reading from a child process, used by byteStringOutput.

Since: 0.1.0.0

Constructors

ByteStringOutputException SomeException (ProcessConfig () () ())

Instances

Exception ByteStringOutputException

Defined in System.Process.Typed.Internal

Methods

toException :: ByteStringOutputException -> SomeException

fromException :: SomeException -> Maybe ByteStringOutputException

displayException :: ByteStringOutputException -> String

Show ByteStringOutputException

Defined in System.Process.Typed.Internal

Methods

showsPrec :: Int -> ByteStringOutputException -> ShowS

show :: ByteStringOutputException -> String

showList :: [ByteStringOutputException] -> ShowS

bracket :: MonadUnliftIO m => IO a -> (a -> IO b) -> (a -> m c) -> m c

finally :: MonadUnliftIO m => m a -> IO () -> m a

nullDevice :: FilePath

The name of the system null device