createProcess

This is the most general way to spawn an external process. The process can be a command line to be executed by a shell or a raw command with a list of arguments. The stdin, stdout, and stderr streams of the new process may individually be attached to new pipes, to existing Handles, or just inherited from the parent (the default.) The details of how to create the process are passed in the CreateProcess record. To make it easier to construct a CreateProcess, the functions proc and shell are supplied that fill in the fields with default values which can be overriden as needed. createProcess returns (mb_stdin_hdl, mb_stdout_hdl, mb_stderr_hdl, ph), where

• if std_in == CreatePipe, then mb_stdin_hdl will be Just h, where h is the write end of the pipe connected to the child process's stdin.
• otherwise, mb_stdin_hdl == Nothing

Similarly for mb_stdout_hdl and mb_stderr_hdl. For example, to execute a simple ls command:

r <- createProcess (proc "ls" [])

To create a pipe from which to read the output of ls:

(_, Just hout, _, _) <-
createProcess (proc "ls" []){ std_out = CreatePipe }

To also set the directory in which to run ls:

(_, Just hout, _, _) <-
createProcess (proc "ls" []){ cwd = Just "/home/bob",
std_out = CreatePipe }

Note that Handles provided for std_in, std_out, or std_err via the UseHandle constructor will be closed by calling this function. This is not always the desired behavior. In cases where you would like to leave the Handle open after spawning the child process, please use createProcess_ instead. All created Handles are initially in text mode; if you need them to be in binary mode then use hSetBinaryMode. ph contains a handle to the running process. On Windows use_process_jobs can be set in CreateProcess in order to create a Win32 Job object to monitor a process tree's progress. If it is set then that job is also returned inside ph. ph can be used to kill all running sub-processes. This feature has been available since 1.5.0.0.

Lifted createProcess.

This is the most general way to spawn an external process. The process can be a command line to be executed by a shell or a raw command with a list of arguments. The stdin, stdout, and stderr streams of the new process may individually be attached to new pipes, to existing Handles, or just inherited from the parent (the default.) The details of how to create the process are passed in the CreateProcess record. To make it easier to construct a CreateProcess, the functions proc and shell are supplied that fill in the fields with default values which can be overriden as needed. createProcess returns (mb_stdin_hdl, mb_stdout_hdl, mb_stderr_hdl, ph), where

• if std_in == CreatePipe, then mb_stdin_hdl will be Just h, where h is the write end of the pipe connected to the child process's stdin.
• otherwise, mb_stdin_hdl == Nothing

Similarly for mb_stdout_hdl and mb_stderr_hdl. For example, to execute a simple ls command:

r <- createProcess (proc "ls" [])

To create a pipe from which to read the output of ls:

(_, Just hout, _, _) <-
createProcess (proc "ls" []){ std_out = CreatePipe }

To also set the directory in which to run ls:

(_, Just hout, _, _) <-
createProcess (proc "ls" []){ cwd = Just "/home/bob",
std_out = CreatePipe }

Note that Handles provided for std_in, std_out, or std_err via the UseHandle constructor will be closed by calling this function. This is not always the desired behavior. In cases where you would like to leave the Handle open after spawning the child process, please use createProcess_ instead. All created Handles are initially in text mode; if you need them to be in binary mode then use hSetBinaryMode.

Calls createProcessConcurrent

This function is almost identical to createProcess. The only differences are:

• Handles provided via UseHandle are not closed automatically.
• This function takes an extra String argument to be used in creating error messages.

This function has been available from the System.Process.Internals module for some time, and is part of the System.Process module since version 1.2.1.0.

Deprecated: This function is scheduled to be replaced by something different in the future, we therefore recommend that you do not use this version and use createProcessGroupFor instead.

createProcessGroupFor pid calls setpgid to make process pid a new process group leader.

Lifted createProcess_.

Mozilla Document.createProcessingInstruction documentation

Mozilla Document.createProcessingInstruction documentation

Functions for launching processes while capturing their output in the logs. Spawn a process with its stdout and stderr connected to the logging system. Every line output by the process will be fed to a debug call.

Spawn a process with its stdout and stderr connected to the logging system.

Spawn a process with its stdout and stderr connected to the logging system. Every line output by the process will be fed to a debug call.

Spawn a process with its stdout and stderr connected to the logging system.

Wrapper around createProcess that prevents multiple processes that are running concurrently from writing to stdout/stderr at the same time. If the process does not output to stdout or stderr, it's run by createProcess entirely as usual. Only processes that can generate output are handled specially: A process is allowed to write to stdout and stderr in the usual way, assuming it can successfully take the output lock. When the output lock is held (ie, by another concurrent process, or because outputConcurrent is being called at the same time), the process is instead run with its stdout and stderr redirected to a buffer. The buffered output will be displayed as soon as the output lock becomes free. Note that the the process is waited for by a background thread, so unlike createProcess, neglecting to call waitForProcess will not result in zombie processess.

Wrapper around createProcess that makes sure a process is run in the foreground, with direct access to stdout and stderr. Useful when eg, running an interactive process. Note that the the process is waited for by a background thread, so unlike createProcess, neglecting to call waitForProcess will not result in zombie processess.

readCreateProcess works exactly like readProcess except that it lets you pass CreateProcess giving better flexibility.

> readCreateProcess ((shell "pwd") { cwd = Just "/etc/" }) ""
"/etc\n"

Note that Handles provided for std_in or std_out via the CreateProcess record will be ignored.

readCreateProcessWithExitCode works exactly like readProcessWithExitCode except that it lets you pass CreateProcess giving better flexibility. Note that Handles provided for std_in, std_out, or std_err via the CreateProcess record will be ignored.