Package org.gnome.gio

Class Subprocess

java.lang.Object

org.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gio.Subprocess

All Implemented Interfaces:

Initable, Proxy

@Generated("io.github.jwharm.JavaGI")
public class Subprocess
extends GObject
implements Initable

GSubprocess allows the creation of and interaction with child processes.

Processes can be communicated with using standard GIO-style APIs (ie: InputStream, OutputStream). 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 OutputStream.spliceAsync(org.gnome.gio.InputStream, java.util.Set<org.gnome.gio.OutputStreamSpliceFlags>, int, org.gnome.gio.Cancellable, org.gnome.gio.AsyncReadyCallback). 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 communicate(byte[], org.gnome.gio.Cancellable, org.javagi.base.Out<byte[]>, org.javagi.base.Out<byte[]>) 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. wait_(org.gnome.gio.Cancellable) 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. By default, the PATH of the current process is used. You can specify G_SUBPROCESS_FLAGS_SEARCH_PATH_FROM_ENVP to use the PATH of the launcher environment instead.

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 Subprocess(). The SubprocessLauncher 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 Subprocess(), followed by waitAsync(org.gnome.gio.Cancellable, org.gnome.gio.AsyncReadyCallback) or wait_(org.gnome.gio.Cancellable). After the process exits, the status can be checked using functions such as getIfExited() (which are similar to the familiar WIFEXITED-style POSIX macros).

Note that as of GLib 2.82, creating a GSubprocess causes the signal SIGPIPE to be ignored for the remainder of the program. If you are writing a command-line utility that uses GSubprocess, you may need to take into account the fact that your program will not automatically be killed if it tries to write to stdout after it has been closed.

Since:

2.40

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Subprocess.Builder<B extends Subprocess.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.

Nested classes/interfaces inherited from class org.gnome.gobject.GObject

GObject.NotifyCallback, GObject.ObjectClass

Nested classes/interfaces inherited from interface org.gnome.gio.Initable

Initable.Initable$Impl, Initable.InitableIface

Constructor Summary

Constructors

Constructor	Description
Subprocess()	Creates a new Subprocess.
Subprocess(@Nullable String @Nullable [] argv, Set<SubprocessFlags> flags)	Create a new process with the given flags and argument list.
Subprocess(@Nullable String @Nullable [] argv, SubprocessFlags... flags)	Create a new process with the given flags and argument list.
Subprocess(MemorySegment address)	Create a Subprocess proxy instance for the provided memory address.

Method Summary

Modifier and Type	Method	Description
protected Subprocess	asParent()	Returns this instance as if it were its parent type.
static Subprocess.Builder<? extends Subprocess.Builder>	builder()	A Subprocess.Builder object constructs a Subprocess with the specified properties.
boolean	communicate(byte @Nullable [] stdinBuf, @Nullable Cancellable cancellable, @Nullable Out<byte[]> stdoutBuf, @Nullable Out<byte[]> stderrBuf)	Communicate with the subprocess until it terminates, and all input and output has been completed.
void	communicateAsync(byte @Nullable [] stdinBuf, @Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)	Asynchronous version of g_subprocess_communicate().
boolean	communicateFinish(AsyncResult result, @Nullable Out<byte[]> stdoutBuf, @Nullable Out<byte[]> stderrBuf)	Complete an invocation of g_subprocess_communicate_async().
boolean	communicateUtf8(@Nullable String stdinBuf, @Nullable Cancellable cancellable, @Nullable Out<String> stdoutBuf, @Nullable 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.
void	communicateUtf8Async(@Nullable String stdinBuf, @Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)	Asynchronous version of g_subprocess_communicate_utf8().
boolean	communicateUtf8Finish(AsyncResult result, @Nullable Out<String> stdoutBuf, @Nullable Out<String> stderrBuf)	Complete an invocation of g_subprocess_communicate_utf8_async().
void	forceExit()	Use an operating-system specific method to attempt an immediate, forceful termination of the process.
int	getExitStatus()	Check the exit status of the subprocess, given that it exited normally.
@Nullable String	getIdentifier()	On UNIX, returns the process ID as a decimal string.
boolean	getIfExited()	Check if the given subprocess exited normally (ie: by way of exit() or return from main()).
boolean	getIfSignaled()	Check if the given subprocess terminated in response to a signal.
int	getStatus()	Gets the raw status code of the process, as from waitpid().
@Nullable InputStream	getStderrPipe()	Gets the GInputStream from which to read the stderr output of subprocess.
@Nullable OutputStream	getStdinPipe()	Gets the GOutputStream that you can write to in order to give data to the stdin of subprocess.
@Nullable InputStream	getStdoutPipe()	Gets the GInputStream from which to read the stdout output of subprocess.
boolean	getSuccessful()	Checks if the process was "successful".
int	getTermSig()	Get the signal number that caused the subprocess to terminate, given that it terminated due to a signal.
static @Nullable Type	getType()	Get the GType of the Subprocess class
void	sendSignal(int signalNum)	Sends the UNIX signal signalNum to the subprocess, if it is still running.
boolean	wait_(@Nullable Cancellable cancellable)	Synchronously wait for the subprocess to terminate.
void	waitAsync(@Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)	Wait for the subprocess to terminate.
boolean	waitCheck(@Nullable Cancellable cancellable)	Combines g_subprocess_wait() with g_spawn_check_wait_status().
void	waitCheckAsync(@Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)	Combines g_subprocess_wait_async() with g_spawn_check_wait_status().
boolean	waitCheckFinish(AsyncResult result)	Collects the result of a previous call to g_subprocess_wait_check_async().
boolean	waitFinish(AsyncResult result)	Collects the result of a previous call to g_subprocess_wait_async().

Methods inherited from class org.gnome.gobject.GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, compatControl, connect, connect, connect, constructed, disconnect, dispatchPropertiesChanged, dispose, dupData, dupQdata, emit, emitNotify, finalize_, forceFloating, freezeNotify, get, getData, getMemoryLayout, getProperty, getProperty, getProperty, getQdata, getv, interfaceFindProperty, interfaceInstallProperty, interfaceListProperties, isFloating, newInstance, newInstance, newv, notify, notify, notifyByPspec, onNotify, ref, refSink, removeToggleRef, removeWeakPointer, replaceData, replaceQdata, runDispose, set, setData, setDataFull, setProperty, setProperty, setProperty, setQdata, setQdataFull, setv, stealData, stealQdata, takeRef, thawNotify, unref, watchClosure, weakRef, weakUnref, withProperties

Methods inherited from class org.gnome.gobject.TypeInstance

callParent, callParent, cast, getPrivate, readGClass, writeGClass

Methods inherited from class org.javagi.base.ProxyInstance

equals, handle, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.gnome.gio.Initable

init

Methods inherited from interface org.javagi.base.Proxy

handle

Constructor Details

Subprocess

public Subprocess(MemorySegment address)

Create a Subprocess proxy instance for the provided memory address.

Parameters:

address - the memory address of the native object

Subprocess

public Subprocess(@Nullable String @Nullable [] argv,
 Set<SubprocessFlags> flags)
           throws GErrorException

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

The argument list is expected to be null-terminated.

Parameters:

argv - commandline arguments for the subprocess

flags - flags that define the behaviour of the subprocess

Throws:

GErrorException - see GError

Since:

2.40

Subprocess

public Subprocess(@Nullable String @Nullable [] argv,
 SubprocessFlags... flags)
           throws GErrorException

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

The argument list is expected to be null-terminated.

Parameters:

argv - commandline arguments for the subprocess

flags - flags that define the behaviour of the subprocess

Throws:

GErrorException - see GError

Since:

2.40

Subprocess

public Subprocess()

Creates a new Subprocess.

Method Details

getType

public static @Nullable Type getType()

Get the GType of the Subprocess class

Returns:

the GType

asParent

protected Subprocess asParent()

Returns this instance as if it were its parent type. This is mostly synonymous to the Java super keyword, but will set the native typeclass function pointers to the parent type. When overriding a native virtual method in Java, "chaining up" with super.methodName() doesn't work, because it invokes the overridden function pointer again. To chain up, call asParent().methodName(). This will call the native function pointer of this virtual method in the typeclass of the parent type.

Overrides:

asParent in class GObject

communicate

public boolean communicate(byte @Nullable [] stdinBuf,
 @Nullable Cancellable cancellable,
 @Nullable Out<byte[]> stdoutBuf,
 @Nullable Out<byte[]> stderrBuf)
                    throws GErrorException

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

If stdinBuf is given, the subprocess must have been created with SubprocessFlags.STDIN_PIPE. The given data is fed to the stdin of the subprocess and the pipe is closed (ie: EOF).

At the same time (as not to cause blocking when dealing with large amounts of data), if SubprocessFlags.STDOUT_PIPE or SubprocessFlags.STDERR_PIPE were used, reads from those streams. The data that was read is returned in stdout and/or the stderr.

If the subprocess was created with SubprocessFlags.STDOUT_PIPE, stdoutBuf will contain the data read from stdout. Otherwise, for subprocesses not created with SubprocessFlags.STDOUT_PIPE, stdoutBuf will be set to null. Similar provisions apply to stderrBuf and SubprocessFlags.STDERR_PIPE.

As usual, any output variable may be given as null to ignore it.

If you desire the stdout and stderr data to be interleaved, create the subprocess with SubprocessFlags.STDOUT_PIPE and SubprocessFlags.STDERR_MERGE. The merged result will be returned in stdoutBuf and stderrBuf will be set to null.

In case of any error (including cancellation), false will be returned with error set. Some or all of the stdin data may have been written. Any stdout or stderr data that has been read will be discarded. None of the out variables (aside from error) will have been set to anything in particular and should not be inspected.

In the case that true is returned, the subprocess has exited and the exit status inspection APIs (eg: g_subprocess_get_if_exited(), g_subprocess_get_exit_status()) may be used.

You should not attempt to use any of the subprocess pipes after starting this function, since they may be left in strange states, even if the operation was cancelled. You should especially not attempt to interact with the pipes while the operation is in progress (either from another thread or if using the asynchronous version).

Parameters:

stdinBuf - data to send to the stdin of the subprocess, or null

cancellable - a GCancellable

stdoutBuf - data read from the subprocess stdout

stderrBuf - data read from the subprocess stderr

Returns:

true if successful

Throws:

GErrorException - see GError

Since:

2.40

communicateAsync

public void communicateAsync(byte @Nullable [] stdinBuf,
 @Nullable Cancellable cancellable,
 @Nullable AsyncReadyCallback callback)

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

Parameters:

stdinBuf - Input data, or null

cancellable - Cancellable

callback - Callback

communicateFinish

public boolean communicateFinish(AsyncResult result,
 @Nullable Out<byte[]> stdoutBuf,
 @Nullable Out<byte[]> stderrBuf)
                          throws GErrorException

Complete an invocation of g_subprocess_communicate_async().

Parameters:

result - Result

stdoutBuf - Return location for stdout data

stderrBuf - Return location for stderr data

Throws:

GErrorException - see GError

communicateUtf8

public boolean communicateUtf8(@Nullable String stdinBuf,
 @Nullable Cancellable cancellable,
 @Nullable Out<String> stdoutBuf,
 @Nullable Out<String> stderrBuf)
                        throws GErrorException

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

On error, stdoutBuf and stderrBuf will be set to undefined values and should not be used.

Parameters:

stdinBuf - data to send to the stdin of the subprocess, or null

cancellable - a GCancellable

stdoutBuf - data read from the subprocess stdout

stderrBuf - data read from the subprocess stderr

Throws:

GErrorException - see GError

communicateUtf8Async

public void communicateUtf8Async(@Nullable String stdinBuf,
 @Nullable Cancellable cancellable,
 @Nullable AsyncReadyCallback callback)

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

Parameters:

stdinBuf - Input data, or null

cancellable - Cancellable

callback - Callback

communicateUtf8Finish

public boolean communicateUtf8Finish(AsyncResult result,
 @Nullable Out<String> stdoutBuf,
 @Nullable Out<String> stderrBuf)
                              throws GErrorException

Complete an invocation of g_subprocess_communicate_utf8_async().

Parameters:

result - Result

stdoutBuf - Return location for stdout data

stderrBuf - Return location for stderr data

Throws:

GErrorException - see GError

forceExit

public 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.

On Unix, this function sends SIGKILL.

Since:

2.40

getExitStatus

public 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.

This is equivalent to the system WEXITSTATUS macro.

It is an error to call this function before g_subprocess_wait() and unless g_subprocess_get_if_exited() returned true.

Returns:

the exit status

Since:

2.40

getIdentifier

public @Nullable String getIdentifier()

On UNIX, returns the process ID as a decimal string. On Windows, returns the result of GetProcessId() also as a string. If the subprocess has terminated, this will return null.

Returns:

the subprocess identifier, or null if the subprocess has terminated

Since:

2.40

getIfExited

public boolean getIfExited()

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

This is equivalent to the system WIFEXITED macro.

It is an error to call this function before g_subprocess_wait() has returned.

Returns:

true if the case of a normal exit

Since:

2.40

getIfSignaled

public boolean getIfSignaled()

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

This is equivalent to the system WIFSIGNALED macro.

It is an error to call this function before g_subprocess_wait() has returned.

Returns:

true if the case of termination due to a signal

Since:

2.40

getStatus

public int getStatus()

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

This value has no particular meaning, but it can be used with the macros defined by the system headers such as WIFEXITED. It can also be used with g_spawn_check_wait_status().

It is more likely that you want to use g_subprocess_get_if_exited() followed by g_subprocess_get_exit_status().

It is an error to call this function before g_subprocess_wait() has returned.

Returns:

the (meaningless) waitpid() exit status from the kernel

Since:

2.40

getStderrPipe

public @Nullable InputStream getStderrPipe()

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

The process must have been created with SubprocessFlags.STDERR_PIPE, otherwise null will be returned.

Returns:

the stderr pipe

Since:

2.40

getStdinPipe

public @Nullable OutputStream getStdinPipe()

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

The process must have been created with SubprocessFlags.STDIN_PIPE and not SubprocessFlags.STDIN_INHERIT, otherwise null will be returned.

Returns:

the stdout pipe

Since:

2.40

getStdoutPipe

public @Nullable InputStream getStdoutPipe()

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

The process must have been created with SubprocessFlags.STDOUT_PIPE, otherwise null will be returned.

Returns:

the stdout pipe

Since:

2.40

getSuccessful

public boolean 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().

It is an error to call this function before g_subprocess_wait() has returned.

Returns:

true if the process exited cleanly with a exit status of 0

Since:

2.40

getTermSig

public int getTermSig()

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

This is equivalent to the system WTERMSIG macro.

It is an error to call this function before g_subprocess_wait() and unless g_subprocess_get_if_signaled() returned true.

Returns:

the signal causing termination

Since:

2.40

sendSignal

public void sendSignal(int signalNum)

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

This API is race-free. If the subprocess has terminated, it will not be signalled.

This API is not available on Windows.

Parameters:

signalNum - the signal number to send

Since:

2.40

wait_

public boolean wait_(@Nullable Cancellable cancellable)
              throws GErrorException

Synchronously wait for the subprocess to terminate.

After the process terminates you can query its exit status with functions such as g_subprocess_get_if_exited() and g_subprocess_get_exit_status().

This function does not fail in the case of the subprocess having abnormal termination. See g_subprocess_wait_check() for that.

Cancelling cancellable doesn't kill the subprocess. Call g_subprocess_force_exit() if it is desirable.

Parameters:

cancellable - a GCancellable

Returns:

true on success, false if cancellable was cancelled

Throws:

GErrorException - see GError

Since:

2.40

waitAsync

public void waitAsync(@Nullable Cancellable cancellable,
 @Nullable AsyncReadyCallback callback)

Wait for the subprocess to terminate.

This is the asynchronous version of g_subprocess_wait().

Parameters:

cancellable - a GCancellable, or null

callback - a GAsyncReadyCallback to call when the operation is complete

Since:

2.40

waitCheck

public boolean waitCheck(@Nullable Cancellable cancellable)
                  throws GErrorException

Combines g_subprocess_wait() with g_spawn_check_wait_status().

Parameters:

cancellable - a GCancellable

Returns:

true on success, false if process exited abnormally, or cancellable was cancelled

Throws:

GErrorException - see GError

Since:

2.40

waitCheckAsync

public void waitCheckAsync(@Nullable Cancellable cancellable,
 @Nullable AsyncReadyCallback callback)

Combines g_subprocess_wait_async() with g_spawn_check_wait_status().

This is the asynchronous version of g_subprocess_wait_check().

Parameters:

cancellable - a GCancellable, or null

callback - a GAsyncReadyCallback to call when the operation is complete

Since:

2.40

waitCheckFinish

public boolean waitCheckFinish(AsyncResult result)
                        throws GErrorException

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

Parameters:

result - the GAsyncResult passed to your GAsyncReadyCallback

Returns:

true if successful, or false with error set

Throws:

GErrorException - see GError

Since:

2.40

waitFinish

public boolean waitFinish(AsyncResult result)
                   throws GErrorException

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

Parameters:

result - the GAsyncResult passed to your GAsyncReadyCallback

Returns:

true if successful, or false with error set

Throws:

GErrorException - see GError

Since:

2.40

builder

public static Subprocess.Builder<? extends Subprocess.Builder> builder()

A Subprocess.Builder object constructs a Subprocess with the specified properties. Use the various set...() methods to set properties, and finish construction with Subprocess.Builder.build().

Returns:

the builder object