Module

Node.ChildProcess

Package
purescript-node-child-process
Repository
purescript-node/purescript-node-child-process

This module contains various types and functions to allow you to spawn and interact with child processes.

It is intended to be imported qualified, as follows:

import Node.ChildProcess (ChildProcess, CHILD_PROCESS)
import Node.ChildProcess as ChildProcess

The Node.js documentation forms the basis for this module and has in-depth documentation about runtime behaviour.

#Handle Source

data Handle :: Type

A handle for inter-process communication (IPC).

#ChildProcess Source

newtype ChildProcess

Opaque type returned by spawn, fork and exec. Needed as input for most methods in this module.

#stdin Source

stdin :: ChildProcess -> Writable ()

The standard input stream of a child process. Note that this is only available if the process was spawned with the stdin option set to "pipe".

#stdout Source

stdout :: ChildProcess -> Readable ()

The standard output stream of a child process. Note that this is only available if the process was spawned with the stdout option set to "pipe".

#stderr Source

stderr :: ChildProcess -> Readable ()

The standard error stream of a child process. Note that this is only available if the process was spawned with the stderr option set to "pipe".

#pid Source

pid :: ChildProcess -> Pid

The process ID of a child process. Note that if the process has already exited, another process may have taken the same ID, so be careful!

#connected Source

connected :: ChildProcess -> Effect Boolean

Indicates whether it is still possible to send and receive messages from the child process.

#kill Source

kill :: Signal -> ChildProcess -> Effect Unit

Send a signal to a child process. In the same way as the unix kill(2) system call, sending a signal to a child process won't necessarily kill it.

The resulting effects of this function depend on the process and the signal. They can vary from system to system. The child process might emit an "error" event if the signal could not be delivered.

#send Source

send :: forall props. {  | props } -> Handle -> ChildProcess -> Effect Boolean

Send messages to the (nodejs) child process.

See the node documentation for in-depth documentation.

#disconnect Source

disconnect :: ChildProcess -> Effect Unit

Closes the IPC channel between parent and child.

#Error Source

type Error = { code :: String, errno :: String, syscall :: String }

An error which occurred inside a child process.

#toStandardError Source

toStandardError :: Error -> Error

Convert a ChildProcess.Error to a standard Error, which can then be thrown inside an Effect or Aff computation (for example).

#Exit Source

data Exit

Specifies how a child process exited; normally (with an exit code), or due to a signal.

Constructors

Instances

#onExit Source

onExit :: ChildProcess -> (Exit -> Effect Unit) -> Effect Unit

Handle the "exit" signal.

#onClose Source

onClose :: ChildProcess -> (Exit -> Effect Unit) -> Effect Unit

Handle the "close" signal.

#onDisconnect Source

onDisconnect :: ChildProcess -> Effect Unit -> Effect Unit

Handle the "disconnect" signal.

#onMessage Source

onMessage :: ChildProcess -> (Foreign -> Maybe Handle -> Effect Unit) -> Effect Unit

Handle the "message" signal.

#onError Source

onError :: ChildProcess -> (Error -> Effect Unit) -> Effect Unit

Handle the "error" signal.

#spawn Source

spawn :: String -> Array String -> SpawnOptions -> Effect ChildProcess

Spawn a child process. Note that, in the event that a child process could not be spawned (for example, if the executable was not found) this will not throw an error. Instead, the ChildProcess will be created anyway, but it will immediately emit an 'error' event.

#SpawnOptions Source

type SpawnOptions = { cwd :: Maybe String, stdio :: Array (Maybe StdIOBehaviour), env :: Maybe (Object String), detached :: Boolean, uid :: Maybe Uid, gid :: Maybe Gid }

Configuration of spawn. Fields set to Nothing will use the node defaults.

#defaultSpawnOptions Source

defaultSpawnOptions :: SpawnOptions

A default set of SpawnOptions. Everything is set to Nothing, detached is false and stdio is ChildProcess.pipe.

#exec Source

exec :: String -> ExecOptions -> (ExecResult -> Effect Unit) -> Effect ChildProcess

Similar to spawn, except that this variant will:

  • run the given command with the shell,
  • buffer output, and wait until the process has exited before calling the callback.

Note that the child process will be killed if the amount of output exceeds a certain threshold (the default is defined by Node.js).

#execFile Source

execFile :: String -> Array String -> ExecOptions -> (ExecResult -> Effect Unit) -> Effect ChildProcess

Like exec, except instead of using a shell, it passes the arguments directly to the specified command.

#ExecOptions Source

type ExecOptions = { cwd :: Maybe String, env :: Maybe (Object String), timeout :: Maybe Number, maxBuffer :: Maybe Int, killSignal :: Maybe Signal, uid :: Maybe Uid, gid :: Maybe Gid }

Configuration of exec. Fields set to Nothing will use the node defaults.

#ExecResult Source

type ExecResult = { stderr :: Buffer, stdout :: Buffer, error :: Maybe Error }

The combined output of a process calld with exec.

#defaultExecOptions Source

defaultExecOptions :: ExecOptions

A default set of ExecOptions. Everything is set to Nothing.

#execSync Source

execSync :: String -> ExecSyncOptions -> Effect Buffer

Generally identical to exec, with the exception that the method will not return until the child process has fully closed. Returns: The stdout from the command.

#execFileSync Source

execFileSync :: String -> Array String -> ExecSyncOptions -> Effect Buffer

Generally identical to execFile, with the exception that the method will not return until the child process has fully closed. Returns: The stdout from the command.

#ExecSyncOptions Source

type ExecSyncOptions = { cwd :: Maybe String, input :: Maybe String, stdio :: Array (Maybe StdIOBehaviour), env :: Maybe (Object String), timeout :: Maybe Number, maxBuffer :: Maybe Int, killSignal :: Maybe Signal, uid :: Maybe Uid, gid :: Maybe Gid }

#fork Source

fork :: String -> Array String -> Effect ChildProcess

A special case of spawn for creating Node.js child processes. The first argument is the module to be run, and the second is the argv (command line arguments).

#StdIOBehaviour Source

data StdIOBehaviour

Behaviour for standard IO streams (eg, standard input, standard output) of a child process.

  • Pipe: creates a pipe between the child and parent process, which can then be accessed as a Stream via the stdin, stdout, or stderr functions.
  • Ignore: ignore this stream. This will cause Node to open /dev/null and connect it to the stream.
  • ShareStream: Connect the supplied stream to the corresponding file descriptor in the child.
  • ShareFD: Connect the supplied file descriptor (which should be open in the parent) to the corresponding file descriptor in the child.

Constructors

#pipe Source

pipe :: Array (Maybe StdIOBehaviour)

Create pipes for each of the three standard IO streams.

#inherit Source

inherit :: Array (Maybe StdIOBehaviour)

Share stdin with stdin, stdout with stdout, and stderr with stderr.

#ignore Source

ignore :: Array (Maybe StdIOBehaviour)

Ignore all streams.