Effectful.Process

Lifted System.Process.

Effect

data Process :: Effect

An effect for running child processes using the process library.

Instances

type DispatchOf Process

Defined in Effectful.Process

type DispatchOf Process = 'Static 'WithSideEffects

data StaticRep Process

Defined in Effectful.Process

data StaticRep Process = Process

Handlers

runProcess :: (HasCallStack, IOE :> es) => Eff (Process : es) a -> Eff es a

Running sub-processes

createProcess :: Process :> es => CreateProcess -> Eff es (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle)

Lifted createProcess.

createProcess_ :: Process :> es => String -> CreateProcess -> Eff es (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle)

Lifted createProcess_.

shell :: String -> CreateProcess

Construct a CreateProcess record for passing to createProcess, representing a command to be passed to the shell.

proc :: FilePath -> [String] -> CreateProcess

Construct a CreateProcess record for passing to createProcess, representing a raw command with arguments.

See RawCommand for precise semantics of the specified FilePath.

data CreateProcess

Constructors

CreateProcess

Fields

• cmdspec :: CmdSpec

  Executable & arguments, or shell command. If cwd is Nothing, relative paths are resolved with respect to the current working directory. If cwd is provided, it is implementation-dependent whether relative paths are resolved with respect to cwd or the current working directory, so absolute paths should be used to ensure portability.

• cwd :: Maybe FilePath

  Optional path to the working directory for the new process

• env :: Maybe [(String, String)]

  Optional environment (otherwise inherit from the current process)

• std_in :: StdStream

  How to determine stdin

• std_out :: StdStream

  How to determine stdout

• std_err :: StdStream

  How to determine stderr

• close_fds :: Bool

  Close all file descriptors except stdin, stdout and stderr in the new process (on Windows, only works if std_in, std_out, and std_err are all Inherit). This implementation will call close on every fd from 3 to the maximum of open files, which can be slow for high maximum of open files.

• create_group :: Bool

  Create a new process group

• delegate_ctlc :: Bool

  Delegate control-C handling. Use this for interactive console processes to let them handle control-C themselves (see below for details).

  On Windows this has no effect.

  Since: process-1.2.0.0

• detach_console :: Bool

  Use the windows DETACHED_PROCESS flag when creating the process; does nothing on other platforms.

  Since: process-1.3.0.0

• create_new_console :: Bool

  Use the windows CREATE_NEW_CONSOLE flag when creating the process; does nothing on other platforms.

  Default: False

  Since: process-1.3.0.0

• new_session :: Bool

  Use posix setsid to start the new process in a new session; does nothing on other platforms.

  Since: process-1.3.0.0

• child_group :: Maybe GroupID

  Use posix setgid to set child process's group id; does nothing on other platforms.

  Default: Nothing

  Since: process-1.4.0.0

• child_user :: Maybe UserID

  Use posix setuid to set child process's user id; does nothing on other platforms.

  Default: Nothing

  Since: process-1.4.0.0

• use_process_jobs :: Bool

  On Windows systems this flag indicates that we should wait for the entire process tree to finish before unblocking. On POSIX systems this flag is ignored. See $exec-on-windows for details.

  Default: False

  Since: process-1.5.0.0

Instances

Show CreateProcess

Defined in System.Process.Common

Methods

showsPrec :: Int -> CreateProcess -> ShowS

show :: CreateProcess -> String

showList :: [CreateProcess] -> ShowS

Eq CreateProcess

Defined in System.Process.Common

Methods

(==) :: CreateProcess -> CreateProcess -> Bool

(/=) :: CreateProcess -> CreateProcess -> Bool

data CmdSpec

Constructors

ShellCommand String

A command line to execute using the shell

RawCommand FilePath [String]

The name of an executable with a list of arguments

The FilePath argument names the executable, and is interpreted according to the platform's standard policy for searching for executables. Specifically:

• on Unix systems the execvp(3) semantics is used, where if the executable filename does not contain a slash (/) then the PATH environment variable is searched for the executable.
• on Windows systems the Win32 CreateProcess semantics is used. Briefly: if the filename does not contain a path, then the directory containing the parent executable is searched, followed by the current directory, then some standard locations, and finally the current PATH. An .exe extension is added if the filename does not already have an extension. For full details see the documentation for the Windows SearchPath API.

Instances

IsString CmdSpec

construct a ShellCommand from a string literal

Since: process-1.2.1.0

Defined in System.Process.Common

Methods

fromString :: String -> CmdSpec

Show CmdSpec

Defined in System.Process.Common

Methods

showsPrec :: Int -> CmdSpec -> ShowS

show :: CmdSpec -> String

showList :: [CmdSpec] -> ShowS

Eq CmdSpec

Defined in System.Process.Common

Methods

(==) :: CmdSpec -> CmdSpec -> Bool

(/=) :: CmdSpec -> CmdSpec -> Bool

data StdStream

Constructors

Inherit

Inherit Handle from parent

UseHandle Handle

Use the supplied Handle

CreatePipe

Create a new pipe. The returned Handle will use the default encoding and newline translation mode (just like Handles created by openFile).

NoStream

Close the stream's file descriptor without passing a Handle. On POSIX systems this may lead to strange behavior in the child process because attempting to read or write after the file has been closed throws an error. This should only be used with child processes that don't use the file descriptor at all. If you wish to ignore the child process's output you should either create a pipe and drain it manually or pass a Handle that writes to /dev/null.

Instances

Show StdStream

Defined in System.Process.Common

Methods

showsPrec :: Int -> StdStream -> ShowS

show :: StdStream -> String

showList :: [StdStream] -> ShowS

Eq StdStream

Defined in System.Process.Common

Methods

(==) :: StdStream -> StdStream -> Bool

(/=) :: StdStream -> StdStream -> Bool

data ProcessHandle

A handle to a process, which can be used to wait for termination of the process using waitForProcess.

None of the process-creation functions in this library wait for termination: they all return a ProcessHandle which may be used to wait for the process later.

On Windows a second wait method can be used to block for event completion. This requires two handles. A process job handle and a events handle to monitor.

Simpler functions for common tasks

callProcess :: Process :> es => FilePath -> [String] -> Eff es ()

Lifted callProcess.

callCommand :: Process :> es => String -> Eff es ()

Lifted callCommand.

spawnProcess :: Process :> es => FilePath -> [String] -> Eff es ProcessHandle

Lifted spawnProcess.

spawnCommand :: Process :> es => String -> Eff es ProcessHandle

Lifted spawnCommand.

readCreateProcess :: Process :> es => CreateProcess -> String -> Eff es String

Lifted readCreateProcess.

readProcess :: Process :> es => FilePath -> [String] -> String -> Eff es String

Lifted readProcess.

readCreateProcessWithExitCode :: Process :> es => CreateProcess -> String -> Eff es (ExitCode, String, String)

Lifted readCreateProcessWithExitCode.

readProcessWithExitCode :: Process :> es => FilePath -> [String] -> String -> Eff es (ExitCode, String, String)

Lifted readProcessWithExitCode.

withCreateProcess :: Process :> es => CreateProcess -> (Maybe Handle -> Maybe Handle -> Maybe Handle -> ProcessHandle -> Eff es a) -> Eff es a

Lifted withCreateProcess.

cleanupProcess :: Process :> es => (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle) -> Eff es ()

Lifted cleanupProcess.

Related utilities

showCommandForUser :: FilePath -> [String] -> String

Given a program p and arguments args, showCommandForUser p args returns a string suitable for pasting into /bin/sh (on Unix systems) or CMD.EXE (on Windows).

type Pid = CPid

The platform specific type for a process identifier.

This is always an integral type. Width and signedness are platform specific.

Since: process-1.6.3.0

getPid :: Process :> es => ProcessHandle -> Eff es (Maybe Pid)

Lifted getPid.

getCurrentPid :: Process :> es => Eff es Pid

Lifted getCurrentPid.

Process completion

waitForProcess :: Process :> es => ProcessHandle -> Eff es ExitCode

Lifted waitForProcess.

getProcessExitCode :: Process :> es => ProcessHandle -> Eff es (Maybe ExitCode)

Lifted getProcessExitCode.

terminateProcess :: Process :> es => ProcessHandle -> Eff es ()

Lifted terminateProcess.

interruptProcessGroupOf :: Process :> es => ProcessHandle -> Eff es ()

Lifted interruptProcessGroupOf.

Interprocess communication

createPipe :: Process :> es => Eff es (Handle, Handle)

Lifted createPipe.

createPipeFd :: Process :> es => Eff es (FD, FD)

Lifted createPipeFd.