Data.Conduit.Process.Typed

Provide input to a process by writing to a conduit. The sink provided here will leave the pipe to the child open after the stream ends. This allows the sink to be used multiple times, but may result in surprising behavior. You may prefer createSinkClose, see https://github.com/snoyberg/conduit/issues/434.

Like createSink, but closes the pipe to the child process as soon as it runs out of data.

Read output from a process by read from a conduit.

Run a process, throwing an exception on a failure exit code. This will store all output from stdout and stderr in memory for better error messages. Note that this will require unbounded memory usage, so caveat emptor.

This will ignore any previous settings for the stdout and stderr streams, and instead force them to use createSource.

Create a ProcessConfig from the given command and arguments.

A running process. The three type parameters provide the type of the standard input, standard output, and standard error streams.

To interact with a Process use the functions from the section Interact with a process.

Defines the exit codes that a program can return.

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.

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.

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

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.

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

Default: inherit

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

Default: inherit

Get the child's standard output stream value.

Get the child's standard error stream value.

Wait for a process to exit, and ensure that it exited successfully. If not, throws an ExitCodeException.

Exceptions thrown by this function will not include stdout or stderr (This prevents unbounded memory usage from reading them into memory). However, some callers such as readProcess_ catch the exception, add the stdout and stderr, and rethrow.

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.

Create a ProcessConfig from the given shell command.

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

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.

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.

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.

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

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.

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.

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.

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

Default: False

Inherit the group from the parent process.

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

Default: False

Inherit the user from the parent process.

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

Default: False

Should we create a new process group?

Default: False

Create new console on Windows, see create_new_console.

Default: False

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

Default: False

Detach console on Windows, see detach_console.

Default: False

Set the environment variables of the child process.

Default: current process's environment.

Inherit the environment variables from the parent process.

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

Default: False

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

Default: inherit

Set the working directory of the child process.

Default: current process's working directory.

Inherit the working directory from the parent process.

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.

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.

Deprecated synonym for withProcessTerm_.

Deprecated synonym for withProcessTerm.

Launch a process based on the given ProcessConfig. You should ensure that you call stopProcess on the result. It's usually better to use one of the functions in this module which ensures stopProcess is called, such as withProcessWait.

Same as checkExitCode, but in STM.

Get an ExitCodeException containing no data other than the exit code and process config.

Unlike checkExitCode and similar, this will return an ExitCodeException even if the process exits with ExitSuccess.

Get an ExitCodeException containing the process's stdout and stderr data.

Note that this will call waitExitCode to block until the process exits, if it has not exited already.

Unlike checkExitCode and similar, this will return an ExitCodeException even if the process exits with ExitSuccess.

Check if a process has exited and, if so, return its ExitCode.

Same as getExitCode, but in STM.

Returns the PID (process ID) of a subprocess.

Nothing is returned if the underlying ProcessHandle was already closed. Otherwise a PID is returned that remains valid as long as the handle is open. The operating system may reuse the PID as soon as the last handle to the process is closed.

Get the child's standard input stream value.

Run a process, capture its standard output and error as a ByteString, wait for it to complete, and then return its exit code, output, and error.

Note that any previously used setStdout or setStderr will be overridden.

Same as readProcess, but interleaves stderr with stdout.

Motivation: Use this function if you need stdout interleaved with stderr output (e.g. from an HTTP server) in order to debug failures.

Same as readProcessInterleaved, but instead of returning the ExitCode, checks it with checkExitCode.

Exceptions thrown by this function will include stdout.

Same as readProcess, but only read the stderr of the process. Original settings for stdout remain.

Same as readProcessStderr, but instead of returning the ExitCode, checks it with checkExitCode.

Exceptions thrown by this function will include stderr.

Same as readProcess, but only read the stdout of the process. Original settings for stderr remain.

Same as readProcessStdout, but instead of returning the ExitCode, checks it with checkExitCode.

Exceptions thrown by this function will include stdout.

Same as readProcess, but instead of returning the ExitCode, checks it with checkExitCode.

Exceptions thrown by this function will include stdout and stderr.

Run the given process, wait for it to exit, and returns its ExitCode.

Same as runProcess, but instead of returning the ExitCode, checks it with checkExitCode.

Close a process and release any resources acquired. This will ensure terminateProcess is called, wait for the process to actually exit, and then close out resources allocated for the streams. In the event of any cleanup exceptions being thrown this will throw an exception.

Take ProcessHandle out of the Process. This method is needed in cases one need to use low level functions from the process package. Use cases for this method are:

1. Send a special signal to the process.

2. Terminate the process group instead of terminating single process.

3. Use platform specific API on the underlying process.

This method is considered unsafe because the actions it performs on the underlying process may overlap with the functionality that typed-process provides. For example the user should not call waitForProcess on the process handle as either waitForProcess or stopProcess will lock. Additionally, even if process was terminated by the terminateProcess or by sending signal, stopProcess should be called either way in order to cleanup resources allocated by the typed-process.

Wait for the process to exit and then return its ExitCode.

Same as waitExitCode, but in STM.

Uses the bracket pattern to call startProcess and ensures that stopProcess is called.

This function is usually not what you want. You're likely better off using withProcessWait. See https://github.com/fpco/typed-process/issues/25.

Same as withProcessTerm, but also calls checkExitCode

To interact with a Process use the functions from the section Interact with a process.

Uses the bracket pattern to call startProcess. Unlike withProcessTerm, this function will wait for the child process to exit, and only kill it with stopProcess in the event that the inner function throws an exception.

To interact with a Process use the functions from the section Interact with a process.

Same as withProcessWait, but also calls checkExitCode

The platform specific type for a process identifier.

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