Subprocess

GSubprocess allows the creation of and interaction with child processes.

Processes can be communicated with using standard GIO-style APIs (ie: GInputStream, GOutputStream). There are GIO-style APIs to wait for process termination (ie: cancellable and with an asynchronous variant).

There is an API to force a process to terminate, as well as a race-free API for sending UNIX signals to a subprocess.

One major advantage that GIO brings over the core GLib library is comprehensive API for asynchronous I/O, such g_output_stream_splice_async(). This makes GSubprocess significantly more powerful and flexible than equivalent APIs in some other languages such as the subprocess.py included with Python. For example, using GSubprocess one could create two child processes, reading standard output from the first, processing it, and writing to the input stream of the second, all without blocking the main loop.

A powerful g_subprocess_communicate() API is provided similar to the `communicate()` method of subprocess.py. This enables very easy interaction with a subprocess that has been opened with pipes.

GSubprocess defaults to tight control over the file descriptors open in the child process, avoiding dangling-fd issues that are caused by a simple fork()/exec(). The only open file descriptors in the spawned process are ones that were explicitly specified by the GSubprocess API (unless G_SUBPROCESS_FLAGS_INHERIT_FDS was specified).

GSubprocess will quickly reap all child processes as they exit, avoiding "zombie processes" remaining around for long periods of time. g_subprocess_wait() can be used to wait for this to happen, but it will happen even without the call being explicitly made.

As a matter of principle, GSubprocess has no API that accepts shell-style space-separated strings. It will, however, match the typical shell behaviour of searching the PATH for executables that do not contain a directory separator in their name.

GSubprocess attempts to have a very simple API for most uses (ie: spawning a subprocess with arguments and support for most typical kinds of input and output redirection). See g_subprocess_new(). The GSubprocessLauncher API is provided for more complicated cases (advanced types of redirection, environment variable manipulation, change of working directory, child setup functions, etc).

A typical use of GSubprocess will involve calling g_subprocess_new(), followed by g_subprocess_wait_async() or g_subprocess_wait(). After the process exits, the status can be checked using functions such as g_subprocess_get_if_exited() (which are similar to the familiar WIFEXITED-style POSIX macros).

Constructors

this
this(GSubprocess* gSubprocess, bool ownedRef = false)

Sets our main struct and passes it to the parent class.

this
this(string[] argv, GSubprocessFlags flags)

Create a new process with the given flags and argument list.

Members

Functions

communicate
bool communicate(Bytes stdinBuf, Cancellable cancellable, out Bytes stdoutBuf, out Bytes stderrBuf)

Communicate with the subprocess until it terminates, and all input and output has been completed.

communicateAsync
void communicateAsync(Bytes stdinBuf, Cancellable cancellable, GAsyncReadyCallback callback, void* userData)

Asynchronous version of g_subprocess_communicate(). Complete invocation with g_subprocess_communicate_finish().

communicateFinish
bool communicateFinish(AsyncResultIF result, out Bytes stdoutBuf, out Bytes stderrBuf)

Complete an invocation of g_subprocess_communicate_async().

communicateUtf8
bool communicateUtf8(string stdinBuf, Cancellable cancellable, out string stdoutBuf, out string stderrBuf)

Like g_subprocess_communicate(), but validates the output of the process as UTF-8, and returns it as a regular NUL terminated string.

communicateUtf8Async
void communicateUtf8Async(string stdinBuf, Cancellable cancellable, GAsyncReadyCallback callback, void* userData)

Asynchronous version of g_subprocess_communicate_utf8(). Complete invocation with g_subprocess_communicate_utf8_finish().

communicateUtf8Finish
bool communicateUtf8Finish(AsyncResultIF result, out string stdoutBuf, out string stderrBuf)

Complete an invocation of g_subprocess_communicate_utf8_async().

forceExit
void forceExit()

Use an operating-system specific method to attempt an immediate, forceful termination of the process. There is no mechanism to determine whether or not the request itself was successful; however, you can use g_subprocess_wait() to monitor the status of the process after calling this function.

getExitStatus
int getExitStatus()

Check the exit status of the subprocess, given that it exited normally. This is the value passed to the exit() system call or the return value from main.

getIdentifier
string getIdentifier()

On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string.

getIfExited
bool getIfExited()

Check if the given subprocess exited normally (ie: by way of exit() or return from main()).

getIfSignaled
bool getIfSignaled()

Check if the given subprocess terminated in response to a signal.

getStatus
int getStatus()

Gets the raw status code of the process, as from waitpid().

getStderrPipe
InputStream getStderrPipe()

Gets the GInputStream from which to read the stderr output of subprocess.

getStdinPipe
OutputStream getStdinPipe()

Gets the GOutputStream that you can write to in order to give data to the stdin of subprocess.

getStdoutPipe
InputStream getStdoutPipe()

Gets the GInputStream from which to read the stdout output of subprocess.

getStruct
void* getStruct()

the main Gtk struct as a void*

getSubprocessStruct
GSubprocess* getSubprocessStruct(bool transferOwnership = false)

Get the main Gtk struct

getSuccessful
bool getSuccessful()

Checks if the process was "successful". A process is considered successful if it exited cleanly with an exit status of 0, either by way of the exit() system call or return from main().

getTermSig
int getTermSig()

Get the signal number that caused the subprocess to terminate, given that it terminated due to a signal.

sendSignal
void sendSignal(int signalNum)

Sends the UNIX signal signal_num to the subprocess, if it is still running.

wait
bool wait(Cancellable cancellable)

Synchronously wait for the subprocess to terminate.

waitAsync
void waitAsync(Cancellable cancellable, GAsyncReadyCallback callback, void* userData)

Wait for the subprocess to terminate.

waitCheck
bool waitCheck(Cancellable cancellable)

Combines g_subprocess_wait() with g_spawn_check_exit_status().

waitCheckAsync
void waitCheckAsync(Cancellable cancellable, GAsyncReadyCallback callback, void* userData)

Combines g_subprocess_wait_async() with g_spawn_check_exit_status().

waitCheckFinish
bool waitCheckFinish(AsyncResultIF result)

Collects the result of a previous call to g_subprocess_wait_check_async().

waitFinish
bool waitFinish(AsyncResultIF result)

Collects the result of a previous call to g_subprocess_wait_async().

Static functions

getType
GType getType()

Variables

gSubprocess
GSubprocess* gSubprocess;

the main Gtk struct

Meta

Since

2.40