| .. currentmodule:: asyncio |
| |
| Subprocess |
| ========== |
| |
| Create a subprocess |
| ------------------- |
| |
| .. function:: create_subprocess_shell(cmd, stdin=None, stdout=None, stderr=None, loop=None, limit=None, \*\*kwds) |
| |
| Run the shell command *cmd* given as a string. Return a :class:`~asyncio.subprocess.Process` |
| instance. |
| |
| This function is a :ref:`coroutine <coroutine>`. |
| |
| .. function:: create_subprocess_exec(\*args, stdin=None, stdout=None, stderr=None, loop=None, limit=None, \*\*kwds) |
| |
| Create a subprocess. Return a :class:`~asyncio.subprocess.Process` instance. |
| |
| This function is a :ref:`coroutine <coroutine>`. |
| |
| Use the :meth:`BaseEventLoop.connect_read_pipe` and |
| :meth:`BaseEventLoop.connect_write_pipe` methods to connect pipes. |
| |
| .. seealso:: |
| |
| The :meth:`BaseEventLoop.subprocess_exec` and |
| :meth:`BaseEventLoop.subprocess_shell` methods. |
| |
| |
| Constants |
| --------- |
| |
| .. data:: asyncio.subprocess.PIPE |
| |
| Special value that can be used as the *stdin*, *stdout* or *stderr* argument |
| to :func:`create_subprocess_shell` and :func:`create_subprocess_exec` and |
| indicates that a pipe to the standard stream should be opened. |
| |
| .. data:: asyncio.subprocess.STDOUT |
| |
| Special value that can be used as the *stderr* argument to |
| :func:`create_subprocess_shell` and :func:`create_subprocess_exec` and |
| indicates that standard error should go into the same handle as standard |
| output. |
| |
| .. data:: asyncio.subprocess.DEVNULL |
| |
| Special value that can be used as the *stderr* argument to |
| :func:`create_subprocess_shell` and :func:`create_subprocess_exec` and |
| indicates that standard error should go into the same handle as standard |
| output. |
| |
| |
| Process |
| ------- |
| |
| .. class:: asyncio.subprocess.Process |
| |
| .. attribute:: pid |
| |
| The identifier of the process. |
| |
| Note that if you set the *shell* argument to ``True``, this is the |
| process identifier of the spawned shell. |
| |
| .. attribute:: returncode |
| |
| Return code of the process when it exited. A ``None`` value indicates |
| that the process has not terminated yet. |
| |
| A negative value ``-N`` indicates that the child was terminated by signal |
| ``N`` (Unix only). |
| |
| .. attribute:: stdin |
| |
| Standard input stream (write), ``None`` if the process was created with |
| ``stdin=None``. |
| |
| .. attribute:: stdout |
| |
| Standard output stream (read), ``None`` if the process was created with |
| ``stdout=None``. |
| |
| .. attribute:: stderr |
| |
| Standard error stream (read), ``None`` if the process was created with |
| ``stderr=None``. |
| |
| .. method:: communicate(input=None) |
| |
| Interact with process: Send data to stdin. Read data from stdout and |
| stderr, until end-of-file is reached. Wait for process to terminate. |
| The optional *input* argument should be data to be sent to the child |
| process, or ``None``, if no data should be sent to the child. The type |
| of *input* must be bytes. |
| |
| :meth:`communicate` returns a tuple ``(stdoutdata, stderrdata)``. |
| |
| Note that if you want to send data to the process's stdin, you need to |
| create the Process object with ``stdin=PIPE``. Similarly, to get anything |
| other than ``None`` in the result tuple, you need to give ``stdout=PIPE`` |
| and/or ``stderr=PIPE`` too. |
| |
| .. note:: |
| |
| The data read is buffered in memory, so do not use this method if the |
| data size is large or unlimited. |
| |
| .. method:: kill() |
| |
| Kills the child. On Posix OSs the function sends :py:data:`SIGKILL` to |
| the child. On Windows :meth:`kill` is an alias for :meth:`terminate`. |
| |
| .. method:: send_signal(signal) |
| |
| Sends the signal *signal* to the child process. |
| |
| .. note:: |
| |
| On Windows, :py:data:`SIGTERM` is an alias for :meth:`terminate`. |
| ``CTRL_C_EVENT`` and ``CTRL_BREAK_EVENT`` can be sent to processes |
| started with a *creationflags* parameter which includes |
| ``CREATE_NEW_PROCESS_GROUP``. |
| |
| .. method:: terminate() |
| |
| Stop the child. On Posix OSs the method sends :py:data:`signal.SIGTERM` |
| to the child. On Windows the Win32 API function |
| :c:func:`TerminateProcess` is called to stop the child. |
| |
| .. method:: wait(self): |
| |
| Wait for child process to terminate. Set and return :attr:`returncode` |
| attribute. |
| |
| |
| Example |
| ------- |
| |
| Implement a function similar to :func:`subprocess.getstatusoutput`, except that |
| it does not use a shell. Get the output of the "python -m platform" command and |
| display the output:: |
| |
| import asyncio |
| import sys |
| from asyncio import subprocess |
| |
| @asyncio.coroutine |
| def getstatusoutput(*args): |
| proc = yield from asyncio.create_subprocess_exec( |
| *args, |
| stdout=subprocess.PIPE, |
| stderr=subprocess.STDOUT) |
| try: |
| stdout, _ = yield from proc.communicate() |
| except: |
| proc.kill() |
| yield from proc.wait() |
| raise |
| exitcode = yield from proc.wait() |
| return (exitcode, stdout) |
| |
| loop = asyncio.get_event_loop() |
| coro = getstatusoutput(sys.executable, '-m', 'platform') |
| exitcode, stdout = loop.run_until_complete(coro) |
| if not exitcode: |
| stdout = stdout.decode('ascii').rstrip() |
| print("Platform: %s" % stdout) |
| else: |
| print("Python failed with exit code %s:" % exitcode) |
| sys.stdout.flush() |
| sys.stdout.buffer.flush() |
| sys.stdout.buffer.write(stdout) |
| sys.stdout.buffer.flush() |
| loop.close() |