Module tenlib.shell
This module allows you to run commands. The functions are simple wrappers for
subprocess.Popen.
If you want to obtain the output of a command, use output():
>>> stdout, stderr = shell.output("ls -alh")
If you're not interested in the output and just want to run a command, use call():
>>> process = shell.call("sleep 3")
Finally, to get a Popen object and have the process run in the background, use
process():
>>> process = shell.process("/bin/process")
>>> process.stdin.write(b"hi\n")
>>> process.stdout.read()
b"hello!\n"
>>> process.stdin.close()
>>> process.wait()
Functions
def process(command: str | list[str], **kwargs) ‑> subprocess.Popen-
Runs process in the background.
Args
command- Command to execute
kwargs- extra arguments for
subprocess.Popen
def call(command: str | list[str], timeout: int = None, **kwargs) ‑> subprocess.Popen-
Runs process to completion. The output (stdout and stderr) is discarded.
Args
command- Command to execute
timeout- If the process does not terminate after timeout seconds, raises a
TimeoutExpiredexception. kwargs- extra arguments for
subprocess.Popen
>>> p = shell.call("ls -alh") >>> stdout = p.stdout.read() def output(command: str | list[str], text: bool = True, timeout: int = None, **kwargs) ‑> tuple[str | bytes, str | bytes]-
Returns the output of the process.
Args
command- Command to execute
text- If True (default), return result as
str. Otherwise,bytes. timeout- If the process does not terminate after timeout seconds, raises a
TimeoutExpiredexception. kwargs- extra arguments for
subprocess.Popen
Returns
tuple[str | bytes, str | bytes]- stdout and stderr, as str or bytes.
Classes
class Popen (args, bufsize=-1, executable=None, stdin=None, stdout=None, stderr=None, preexec_fn=None, close_fds=True, shell=False, cwd=None, env=None, universal_newlines=None, startupinfo=None, creationflags=0, restore_signals=True, start_new_session=False, pass_fds=(), *, user=None, group=None, extra_groups=None, encoding=None, errors=None, text=None, umask=-1, pipesize=-1)-
Execute a child program in a new process.
For a complete description of the arguments see the Python documentation.
Arguments
args: A string, or a sequence of program arguments.
bufsize: supplied as the buffering argument to the open() function when creating the stdin/stdout/stderr pipe file objects
executable: A replacement program to execute.
stdin, stdout and stderr: These specify the executed programs' standard input, standard output and standard error file handles, respectively.
preexec_fn: (POSIX only) An object to be called in the child process just before the child is executed.
close_fds: Controls closing or inheriting of file descriptors.
shell: If true, the command will be executed through the shell.
cwd: Sets the current directory before the child is executed.
env: Defines the environment variables for the new process.
text: If true, decode stdin, stdout and stderr using the given encoding (if set) or the system default otherwise.
universal_newlines: Alias of text, provided for backwards compatibility.
startupinfo and creationflags (Windows only)
restore_signals (POSIX only)
start_new_session (POSIX only)
group (POSIX only)
extra_groups (POSIX only)
user (POSIX only)
umask (POSIX only)
pass_fds (POSIX only)
encoding and errors: Text mode encoding and error handling to use for file objects stdin, stdout and stderr.
Attributes
stdin, stdout, stderr, pid, returncode Create new Popen instance.
Expand source code
class Popen: """ Execute a child program in a new process. For a complete description of the arguments see the Python documentation. Arguments: args: A string, or a sequence of program arguments. bufsize: supplied as the buffering argument to the open() function when creating the stdin/stdout/stderr pipe file objects executable: A replacement program to execute. stdin, stdout and stderr: These specify the executed programs' standard input, standard output and standard error file handles, respectively. preexec_fn: (POSIX only) An object to be called in the child process just before the child is executed. close_fds: Controls closing or inheriting of file descriptors. shell: If true, the command will be executed through the shell. cwd: Sets the current directory before the child is executed. env: Defines the environment variables for the new process. text: If true, decode stdin, stdout and stderr using the given encoding (if set) or the system default otherwise. universal_newlines: Alias of text, provided for backwards compatibility. startupinfo and creationflags (Windows only) restore_signals (POSIX only) start_new_session (POSIX only) group (POSIX only) extra_groups (POSIX only) user (POSIX only) umask (POSIX only) pass_fds (POSIX only) encoding and errors: Text mode encoding and error handling to use for file objects stdin, stdout and stderr. Attributes: stdin, stdout, stderr, pid, returncode """ _child_created = False # Set here since __del__ checks it def __init__(self, args, bufsize=-1, executable=None, stdin=None, stdout=None, stderr=None, preexec_fn=None, close_fds=True, shell=False, cwd=None, env=None, universal_newlines=None, startupinfo=None, creationflags=0, restore_signals=True, start_new_session=False, pass_fds=(), *, user=None, group=None, extra_groups=None, encoding=None, errors=None, text=None, umask=-1, pipesize=-1): """Create new Popen instance.""" _cleanup() # Held while anything is calling waitpid before returncode has been # updated to prevent clobbering returncode if wait() or poll() are # called from multiple threads at once. After acquiring the lock, # code must re-check self.returncode to see if another thread just # finished a waitpid() call. self._waitpid_lock = threading.Lock() self._input = None self._communication_started = False if bufsize is None: bufsize = -1 # Restore default if not isinstance(bufsize, int): raise TypeError("bufsize must be an integer") if pipesize is None: pipesize = -1 # Restore default if not isinstance(pipesize, int): raise TypeError("pipesize must be an integer") if _mswindows: if preexec_fn is not None: raise ValueError("preexec_fn is not supported on Windows " "platforms") else: # POSIX if pass_fds and not close_fds: warnings.warn("pass_fds overriding close_fds.", RuntimeWarning) close_fds = True if startupinfo is not None: raise ValueError("startupinfo is only supported on Windows " "platforms") if creationflags != 0: raise ValueError("creationflags is only supported on Windows " "platforms") self.args = args self.stdin = None self.stdout = None self.stderr = None self.pid = None self.returncode = None self.encoding = encoding self.errors = errors self.pipesize = pipesize # Validate the combinations of text and universal_newlines if (text is not None and universal_newlines is not None and bool(universal_newlines) != bool(text)): raise SubprocessError('Cannot disambiguate when both text ' 'and universal_newlines are supplied but ' 'different. Pass one or the other.') # Input and output objects. The general principle is like # this: # # Parent Child # ------ ----- # p2cwrite ---stdin---> p2cread # c2pread <--stdout--- c2pwrite # errread <--stderr--- errwrite # # On POSIX, the child objects are file descriptors. On # Windows, these are Windows file handles. The parent objects # are file descriptors on both platforms. The parent objects # are -1 when not using PIPEs. The child objects are -1 # when not redirecting. (p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) = self._get_handles(stdin, stdout, stderr) # We wrap OS handles *before* launching the child, otherwise a # quickly terminating child could make our fds unwrappable # (see #8458). if _mswindows: if p2cwrite != -1: p2cwrite = msvcrt.open_osfhandle(p2cwrite.Detach(), 0) if c2pread != -1: c2pread = msvcrt.open_osfhandle(c2pread.Detach(), 0) if errread != -1: errread = msvcrt.open_osfhandle(errread.Detach(), 0) self.text_mode = encoding or errors or text or universal_newlines # PEP 597: We suppress the EncodingWarning in subprocess module # for now (at Python 3.10), because we focus on files for now. # This will be changed to encoding = io.text_encoding(encoding) # in the future. if self.text_mode and encoding is None: self.encoding = encoding = "locale" # How long to resume waiting on a child after the first ^C. # There is no right value for this. The purpose is to be polite # yet remain good for interactive users trying to exit a tool. self._sigint_wait_secs = 0.25 # 1/xkcd221.getRandomNumber() self._closed_child_pipe_fds = False if self.text_mode: if bufsize == 1: line_buffering = True # Use the default buffer size for the underlying binary streams # since they don't support line buffering. bufsize = -1 else: line_buffering = False gid = None if group is not None: if not hasattr(os, 'setregid'): raise ValueError("The 'group' parameter is not supported on the " "current platform") elif isinstance(group, str): try: import grp except ImportError: raise ValueError("The group parameter cannot be a string " "on systems without the grp module") gid = grp.getgrnam(group).gr_gid elif isinstance(group, int): gid = group else: raise TypeError("Group must be a string or an integer, not {}" .format(type(group))) if gid < 0: raise ValueError(f"Group ID cannot be negative, got {gid}") gids = None if extra_groups is not None: if not hasattr(os, 'setgroups'): raise ValueError("The 'extra_groups' parameter is not " "supported on the current platform") elif isinstance(extra_groups, str): raise ValueError("Groups must be a list, not a string") gids = [] for extra_group in extra_groups: if isinstance(extra_group, str): try: import grp except ImportError: raise ValueError("Items in extra_groups cannot be " "strings on systems without the " "grp module") gids.append(grp.getgrnam(extra_group).gr_gid) elif isinstance(extra_group, int): gids.append(extra_group) else: raise TypeError("Items in extra_groups must be a string " "or integer, not {}" .format(type(extra_group))) # make sure that the gids are all positive here so we can do less # checking in the C code for gid_check in gids: if gid_check < 0: raise ValueError(f"Group ID cannot be negative, got {gid_check}") uid = None if user is not None: if not hasattr(os, 'setreuid'): raise ValueError("The 'user' parameter is not supported on " "the current platform") elif isinstance(user, str): try: import pwd except ImportError: raise ValueError("The user parameter cannot be a string " "on systems without the pwd module") uid = pwd.getpwnam(user).pw_uid elif isinstance(user, int): uid = user else: raise TypeError("User must be a string or an integer") if uid < 0: raise ValueError(f"User ID cannot be negative, got {uid}") try: if p2cwrite != -1: self.stdin = io.open(p2cwrite, 'wb', bufsize) if self.text_mode: self.stdin = io.TextIOWrapper(self.stdin, write_through=True, line_buffering=line_buffering, encoding=encoding, errors=errors) if c2pread != -1: self.stdout = io.open(c2pread, 'rb', bufsize) if self.text_mode: self.stdout = io.TextIOWrapper(self.stdout, encoding=encoding, errors=errors) if errread != -1: self.stderr = io.open(errread, 'rb', bufsize) if self.text_mode: self.stderr = io.TextIOWrapper(self.stderr, encoding=encoding, errors=errors) self._execute_child(args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, restore_signals, gid, gids, uid, umask, start_new_session) except: # Cleanup if the child failed starting. for f in filter(None, (self.stdin, self.stdout, self.stderr)): try: f.close() except OSError: pass # Ignore EBADF or other errors. if not self._closed_child_pipe_fds: to_close = [] if stdin == PIPE: to_close.append(p2cread) if stdout == PIPE: to_close.append(c2pwrite) if stderr == PIPE: to_close.append(errwrite) if hasattr(self, '_devnull'): to_close.append(self._devnull) for fd in to_close: try: if _mswindows and isinstance(fd, Handle): fd.Close() else: os.close(fd) except OSError: pass raise def __repr__(self): obj_repr = ( f"<{self.__class__.__name__}: " f"returncode: {self.returncode} args: {self.args!r}>" ) if len(obj_repr) > 80: obj_repr = obj_repr[:76] + "...>" return obj_repr __class_getitem__ = classmethod(types.GenericAlias) @property def universal_newlines(self): # universal_newlines as retained as an alias of text_mode for API # compatibility. bpo-31756 return self.text_mode @universal_newlines.setter def universal_newlines(self, universal_newlines): self.text_mode = bool(universal_newlines) def _translate_newlines(self, data, encoding, errors): data = data.decode(encoding, errors) return data.replace("\r\n", "\n").replace("\r", "\n") def __enter__(self): return self def __exit__(self, exc_type, value, traceback): if self.stdout: self.stdout.close() if self.stderr: self.stderr.close() try: # Flushing a BufferedWriter may raise an error if self.stdin: self.stdin.close() finally: if exc_type == KeyboardInterrupt: # https://bugs.python.org/issue25942 # In the case of a KeyboardInterrupt we assume the SIGINT # was also already sent to our child processes. We can't # block indefinitely as that is not user friendly. # If we have not already waited a brief amount of time in # an interrupted .wait() or .communicate() call, do so here # for consistency. if self._sigint_wait_secs > 0: try: self._wait(timeout=self._sigint_wait_secs) except TimeoutExpired: pass self._sigint_wait_secs = 0 # Note that this has been done. return # resume the KeyboardInterrupt # Wait for the process to terminate, to avoid zombies. self.wait() def __del__(self, _maxsize=sys.maxsize, _warn=warnings.warn): if not self._child_created: # We didn't get to successfully create a child process. return if self.returncode is None: # Not reading subprocess exit status creates a zombie process which # is only destroyed at the parent python process exit _warn("subprocess %s is still running" % self.pid, ResourceWarning, source=self) # In case the child hasn't been waited on, check if it's done. self._internal_poll(_deadstate=_maxsize) if self.returncode is None and _active is not None: # Child is still running, keep us alive until we can wait on it. _active.append(self) def _get_devnull(self): if not hasattr(self, '_devnull'): self._devnull = os.open(os.devnull, os.O_RDWR) return self._devnull def _stdin_write(self, input): if input: try: self.stdin.write(input) except BrokenPipeError: pass # communicate() must ignore broken pipe errors. except OSError as exc: if exc.errno == errno.EINVAL: # bpo-19612, bpo-30418: On Windows, stdin.write() fails # with EINVAL if the child process exited or if the child # process is still running but closed the pipe. pass else: raise try: self.stdin.close() except BrokenPipeError: pass # communicate() must ignore broken pipe errors. except OSError as exc: if exc.errno == errno.EINVAL: pass else: raise def communicate(self, input=None, timeout=None): """Interact with process: Send data to stdin and close it. 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. communicate() returns a tuple (stdout, stderr). By default, all communication is in bytes, and therefore any "input" should be bytes, and the (stdout, stderr) will be bytes. If in text mode (indicated by self.text_mode), any "input" should be a string, and (stdout, stderr) will be strings decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines. """ if self._communication_started and input: raise ValueError("Cannot send input after starting communication") # Optimization: If we are not worried about timeouts, we haven't # started communicating, and we have one or zero pipes, using select() # or threads is unnecessary. if (timeout is None and not self._communication_started and [self.stdin, self.stdout, self.stderr].count(None) >= 2): stdout = None stderr = None if self.stdin: self._stdin_write(input) elif self.stdout: stdout = self.stdout.read() self.stdout.close() elif self.stderr: stderr = self.stderr.read() self.stderr.close() self.wait() else: if timeout is not None: endtime = _time() + timeout else: endtime = None try: stdout, stderr = self._communicate(input, endtime, timeout) except KeyboardInterrupt: # https://bugs.python.org/issue25942 # See the detailed comment in .wait(). if timeout is not None: sigint_timeout = min(self._sigint_wait_secs, self._remaining_time(endtime)) else: sigint_timeout = self._sigint_wait_secs self._sigint_wait_secs = 0 # nothing else should wait. try: self._wait(timeout=sigint_timeout) except TimeoutExpired: pass raise # resume the KeyboardInterrupt finally: self._communication_started = True sts = self.wait(timeout=self._remaining_time(endtime)) return (stdout, stderr) def poll(self): """Check if child process has terminated. Set and return returncode attribute.""" return self._internal_poll() def _remaining_time(self, endtime): """Convenience for _communicate when computing timeouts.""" if endtime is None: return None else: return endtime - _time() def _check_timeout(self, endtime, orig_timeout, stdout_seq, stderr_seq, skip_check_and_raise=False): """Convenience for checking if a timeout has expired.""" if endtime is None: return if skip_check_and_raise or _time() > endtime: raise TimeoutExpired( self.args, orig_timeout, output=b''.join(stdout_seq) if stdout_seq else None, stderr=b''.join(stderr_seq) if stderr_seq else None) def wait(self, timeout=None): """Wait for child process to terminate; returns self.returncode.""" if timeout is not None: endtime = _time() + timeout try: return self._wait(timeout=timeout) except KeyboardInterrupt: # https://bugs.python.org/issue25942 # The first keyboard interrupt waits briefly for the child to # exit under the common assumption that it also received the ^C # generated SIGINT and will exit rapidly. if timeout is not None: sigint_timeout = min(self._sigint_wait_secs, self._remaining_time(endtime)) else: sigint_timeout = self._sigint_wait_secs self._sigint_wait_secs = 0 # nothing else should wait. try: self._wait(timeout=sigint_timeout) except TimeoutExpired: pass raise # resume the KeyboardInterrupt def _close_pipe_fds(self, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite): # self._devnull is not always defined. devnull_fd = getattr(self, '_devnull', None) with contextlib.ExitStack() as stack: if _mswindows: if p2cread != -1: stack.callback(p2cread.Close) if c2pwrite != -1: stack.callback(c2pwrite.Close) if errwrite != -1: stack.callback(errwrite.Close) else: if p2cread != -1 and p2cwrite != -1 and p2cread != devnull_fd: stack.callback(os.close, p2cread) if c2pwrite != -1 and c2pread != -1 and c2pwrite != devnull_fd: stack.callback(os.close, c2pwrite) if errwrite != -1 and errread != -1 and errwrite != devnull_fd: stack.callback(os.close, errwrite) if devnull_fd is not None: stack.callback(os.close, devnull_fd) # Prevent a double close of these handles/fds from __init__ on error. self._closed_child_pipe_fds = True if _mswindows: # # Windows methods # def _get_handles(self, stdin, stdout, stderr): """Construct and return tuple with IO objects: p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite """ if stdin is None and stdout is None and stderr is None: return (-1, -1, -1, -1, -1, -1) p2cread, p2cwrite = -1, -1 c2pread, c2pwrite = -1, -1 errread, errwrite = -1, -1 if stdin is None: p2cread = _winapi.GetStdHandle(_winapi.STD_INPUT_HANDLE) if p2cread is None: p2cread, _ = _winapi.CreatePipe(None, 0) p2cread = Handle(p2cread) _winapi.CloseHandle(_) elif stdin == PIPE: p2cread, p2cwrite = _winapi.CreatePipe(None, 0) p2cread, p2cwrite = Handle(p2cread), Handle(p2cwrite) elif stdin == DEVNULL: p2cread = msvcrt.get_osfhandle(self._get_devnull()) elif isinstance(stdin, int): p2cread = msvcrt.get_osfhandle(stdin) else: # Assuming file-like object p2cread = msvcrt.get_osfhandle(stdin.fileno()) p2cread = self._make_inheritable(p2cread) if stdout is None: c2pwrite = _winapi.GetStdHandle(_winapi.STD_OUTPUT_HANDLE) if c2pwrite is None: _, c2pwrite = _winapi.CreatePipe(None, 0) c2pwrite = Handle(c2pwrite) _winapi.CloseHandle(_) elif stdout == PIPE: c2pread, c2pwrite = _winapi.CreatePipe(None, 0) c2pread, c2pwrite = Handle(c2pread), Handle(c2pwrite) elif stdout == DEVNULL: c2pwrite = msvcrt.get_osfhandle(self._get_devnull()) elif isinstance(stdout, int): c2pwrite = msvcrt.get_osfhandle(stdout) else: # Assuming file-like object c2pwrite = msvcrt.get_osfhandle(stdout.fileno()) c2pwrite = self._make_inheritable(c2pwrite) if stderr is None: errwrite = _winapi.GetStdHandle(_winapi.STD_ERROR_HANDLE) if errwrite is None: _, errwrite = _winapi.CreatePipe(None, 0) errwrite = Handle(errwrite) _winapi.CloseHandle(_) elif stderr == PIPE: errread, errwrite = _winapi.CreatePipe(None, 0) errread, errwrite = Handle(errread), Handle(errwrite) elif stderr == STDOUT: errwrite = c2pwrite elif stderr == DEVNULL: errwrite = msvcrt.get_osfhandle(self._get_devnull()) elif isinstance(stderr, int): errwrite = msvcrt.get_osfhandle(stderr) else: # Assuming file-like object errwrite = msvcrt.get_osfhandle(stderr.fileno()) errwrite = self._make_inheritable(errwrite) return (p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) def _make_inheritable(self, handle): """Return a duplicate of handle, which is inheritable""" h = _winapi.DuplicateHandle( _winapi.GetCurrentProcess(), handle, _winapi.GetCurrentProcess(), 0, 1, _winapi.DUPLICATE_SAME_ACCESS) return Handle(h) def _filter_handle_list(self, handle_list): """Filter out console handles that can't be used in lpAttributeList["handle_list"] and make sure the list isn't empty. This also removes duplicate handles.""" # An handle with it's lowest two bits set might be a special console # handle that if passed in lpAttributeList["handle_list"], will # cause it to fail. return list({handle for handle in handle_list if handle & 0x3 != 0x3 or _winapi.GetFileType(handle) != _winapi.FILE_TYPE_CHAR}) def _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, unused_restore_signals, unused_gid, unused_gids, unused_uid, unused_umask, unused_start_new_session): """Execute program (MS Windows version)""" assert not pass_fds, "pass_fds not supported on Windows." if isinstance(args, str): pass elif isinstance(args, bytes): if shell: raise TypeError('bytes args is not allowed on Windows') args = list2cmdline([args]) elif isinstance(args, os.PathLike): if shell: raise TypeError('path-like args is not allowed when ' 'shell is true') args = list2cmdline([args]) else: args = list2cmdline(args) if executable is not None: executable = os.fsdecode(executable) # Process startup details if startupinfo is None: startupinfo = STARTUPINFO() else: # bpo-34044: Copy STARTUPINFO since it is modified above, # so the caller can reuse it multiple times. startupinfo = startupinfo.copy() use_std_handles = -1 not in (p2cread, c2pwrite, errwrite) if use_std_handles: startupinfo.dwFlags |= _winapi.STARTF_USESTDHANDLES startupinfo.hStdInput = p2cread startupinfo.hStdOutput = c2pwrite startupinfo.hStdError = errwrite attribute_list = startupinfo.lpAttributeList have_handle_list = bool(attribute_list and "handle_list" in attribute_list and attribute_list["handle_list"]) # If we were given an handle_list or need to create one if have_handle_list or (use_std_handles and close_fds): if attribute_list is None: attribute_list = startupinfo.lpAttributeList = {} handle_list = attribute_list["handle_list"] = \ list(attribute_list.get("handle_list", [])) if use_std_handles: handle_list += [int(p2cread), int(c2pwrite), int(errwrite)] handle_list[:] = self._filter_handle_list(handle_list) if handle_list: if not close_fds: warnings.warn("startupinfo.lpAttributeList['handle_list'] " "overriding close_fds", RuntimeWarning) # When using the handle_list we always request to inherit # handles but the only handles that will be inherited are # the ones in the handle_list close_fds = False if shell: startupinfo.dwFlags |= _winapi.STARTF_USESHOWWINDOW startupinfo.wShowWindow = _winapi.SW_HIDE if not executable: # gh-101283: without a fully-qualified path, before Windows # checks the system directories, it first looks in the # application directory, and also the current directory if # NeedCurrentDirectoryForExePathW(ExeName) is true, so try # to avoid executing unqualified "cmd.exe". comspec = os.environ.get('ComSpec') if not comspec: system_root = os.environ.get('SystemRoot', '') comspec = os.path.join(system_root, 'System32', 'cmd.exe') if not os.path.isabs(comspec): raise FileNotFoundError('shell not found: neither %ComSpec% nor %SystemRoot% is set') if os.path.isabs(comspec): executable = comspec else: comspec = executable args = '{} /c "{}"'.format (comspec, args) if cwd is not None: cwd = os.fsdecode(cwd) sys.audit("subprocess.Popen", executable, args, cwd, env) # Start the process try: hp, ht, pid, tid = _winapi.CreateProcess(executable, args, # no special security None, None, int(not close_fds), creationflags, env, cwd, startupinfo) finally: # Child is launched. Close the parent's copy of those pipe # handles that only the child should have open. You need # to make sure that no handles to the write end of the # output pipe are maintained in this process or else the # pipe will not close when the child process exits and the # ReadFile will hang. self._close_pipe_fds(p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) # Retain the process handle, but close the thread handle self._child_created = True self._handle = Handle(hp) self.pid = pid _winapi.CloseHandle(ht) def _internal_poll(self, _deadstate=None, _WaitForSingleObject=_winapi.WaitForSingleObject, _WAIT_OBJECT_0=_winapi.WAIT_OBJECT_0, _GetExitCodeProcess=_winapi.GetExitCodeProcess): """Check if child process has terminated. Returns returncode attribute. This method is called by __del__, so it can only refer to objects in its local scope. """ if self.returncode is None: if _WaitForSingleObject(self._handle, 0) == _WAIT_OBJECT_0: self.returncode = _GetExitCodeProcess(self._handle) return self.returncode def _wait(self, timeout): """Internal implementation of wait() on Windows.""" if timeout is None: timeout_millis = _winapi.INFINITE else: timeout_millis = int(timeout * 1000) if self.returncode is None: # API note: Returns immediately if timeout_millis == 0. result = _winapi.WaitForSingleObject(self._handle, timeout_millis) if result == _winapi.WAIT_TIMEOUT: raise TimeoutExpired(self.args, timeout) self.returncode = _winapi.GetExitCodeProcess(self._handle) return self.returncode def _readerthread(self, fh, buffer): buffer.append(fh.read()) fh.close() def _communicate(self, input, endtime, orig_timeout): # Start reader threads feeding into a list hanging off of this # object, unless they've already been started. if self.stdout and not hasattr(self, "_stdout_buff"): self._stdout_buff = [] self.stdout_thread = \ threading.Thread(target=self._readerthread, args=(self.stdout, self._stdout_buff)) self.stdout_thread.daemon = True self.stdout_thread.start() if self.stderr and not hasattr(self, "_stderr_buff"): self._stderr_buff = [] self.stderr_thread = \ threading.Thread(target=self._readerthread, args=(self.stderr, self._stderr_buff)) self.stderr_thread.daemon = True self.stderr_thread.start() if self.stdin: self._stdin_write(input) # Wait for the reader threads, or time out. If we time out, the # threads remain reading and the fds left open in case the user # calls communicate again. if self.stdout is not None: self.stdout_thread.join(self._remaining_time(endtime)) if self.stdout_thread.is_alive(): raise TimeoutExpired(self.args, orig_timeout) if self.stderr is not None: self.stderr_thread.join(self._remaining_time(endtime)) if self.stderr_thread.is_alive(): raise TimeoutExpired(self.args, orig_timeout) # Collect the output from and close both pipes, now that we know # both have been read successfully. stdout = None stderr = None if self.stdout: stdout = self._stdout_buff self.stdout.close() if self.stderr: stderr = self._stderr_buff self.stderr.close() # All data exchanged. Translate lists into strings. stdout = stdout[0] if stdout else None stderr = stderr[0] if stderr else None return (stdout, stderr) def send_signal(self, sig): """Send a signal to the process.""" # Don't signal a process that we know has already died. if self.returncode is not None: return if sig == signal.SIGTERM: self.terminate() elif sig == signal.CTRL_C_EVENT: os.kill(self.pid, signal.CTRL_C_EVENT) elif sig == signal.CTRL_BREAK_EVENT: os.kill(self.pid, signal.CTRL_BREAK_EVENT) else: raise ValueError("Unsupported signal: {}".format(sig)) def terminate(self): """Terminates the process.""" # Don't terminate a process that we know has already died. if self.returncode is not None: return try: _winapi.TerminateProcess(self._handle, 1) except PermissionError: # ERROR_ACCESS_DENIED (winerror 5) is received when the # process already died. rc = _winapi.GetExitCodeProcess(self._handle) if rc == _winapi.STILL_ACTIVE: raise self.returncode = rc kill = terminate else: # # POSIX methods # def _get_handles(self, stdin, stdout, stderr): """Construct and return tuple with IO objects: p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite """ p2cread, p2cwrite = -1, -1 c2pread, c2pwrite = -1, -1 errread, errwrite = -1, -1 if stdin is None: pass elif stdin == PIPE: p2cread, p2cwrite = os.pipe() if self.pipesize > 0 and hasattr(fcntl, "F_SETPIPE_SZ"): fcntl.fcntl(p2cwrite, fcntl.F_SETPIPE_SZ, self.pipesize) elif stdin == DEVNULL: p2cread = self._get_devnull() elif isinstance(stdin, int): p2cread = stdin else: # Assuming file-like object p2cread = stdin.fileno() if stdout is None: pass elif stdout == PIPE: c2pread, c2pwrite = os.pipe() if self.pipesize > 0 and hasattr(fcntl, "F_SETPIPE_SZ"): fcntl.fcntl(c2pwrite, fcntl.F_SETPIPE_SZ, self.pipesize) elif stdout == DEVNULL: c2pwrite = self._get_devnull() elif isinstance(stdout, int): c2pwrite = stdout else: # Assuming file-like object c2pwrite = stdout.fileno() if stderr is None: pass elif stderr == PIPE: errread, errwrite = os.pipe() if self.pipesize > 0 and hasattr(fcntl, "F_SETPIPE_SZ"): fcntl.fcntl(errwrite, fcntl.F_SETPIPE_SZ, self.pipesize) elif stderr == STDOUT: if c2pwrite != -1: errwrite = c2pwrite else: # child's stdout is not set, use parent's stdout errwrite = sys.__stdout__.fileno() elif stderr == DEVNULL: errwrite = self._get_devnull() elif isinstance(stderr, int): errwrite = stderr else: # Assuming file-like object errwrite = stderr.fileno() return (p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) def _posix_spawn(self, args, executable, env, restore_signals, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite): """Execute program using os.posix_spawn().""" if env is None: env = os.environ kwargs = {} if restore_signals: # See _Py_RestoreSignals() in Python/pylifecycle.c sigset = [] for signame in ('SIGPIPE', 'SIGXFZ', 'SIGXFSZ'): signum = getattr(signal, signame, None) if signum is not None: sigset.append(signum) kwargs['setsigdef'] = sigset file_actions = [] for fd in (p2cwrite, c2pread, errread): if fd != -1: file_actions.append((os.POSIX_SPAWN_CLOSE, fd)) for fd, fd2 in ( (p2cread, 0), (c2pwrite, 1), (errwrite, 2), ): if fd != -1: file_actions.append((os.POSIX_SPAWN_DUP2, fd, fd2)) if file_actions: kwargs['file_actions'] = file_actions self.pid = os.posix_spawn(executable, args, env, **kwargs) self._child_created = True self._close_pipe_fds(p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) def _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, restore_signals, gid, gids, uid, umask, start_new_session): """Execute program (POSIX version)""" if isinstance(args, (str, bytes)): args = [args] elif isinstance(args, os.PathLike): if shell: raise TypeError('path-like args is not allowed when ' 'shell is true') args = [args] else: args = list(args) if shell: # On Android the default shell is at '/system/bin/sh'. unix_shell = ('/system/bin/sh' if hasattr(sys, 'getandroidapilevel') else '/bin/sh') args = [unix_shell, "-c"] + args if executable: args[0] = executable if executable is None: executable = args[0] sys.audit("subprocess.Popen", executable, args, cwd, env) if (_USE_POSIX_SPAWN and os.path.dirname(executable) and preexec_fn is None and not close_fds and not pass_fds and cwd is None and (p2cread == -1 or p2cread > 2) and (c2pwrite == -1 or c2pwrite > 2) and (errwrite == -1 or errwrite > 2) and not start_new_session and gid is None and gids is None and uid is None and umask < 0): self._posix_spawn(args, executable, env, restore_signals, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) return orig_executable = executable # For transferring possible exec failure from child to parent. # Data format: "exception name:hex errno:description" # Pickle is not used; it is complex and involves memory allocation. errpipe_read, errpipe_write = os.pipe() # errpipe_write must not be in the standard io 0, 1, or 2 fd range. low_fds_to_close = [] while errpipe_write < 3: low_fds_to_close.append(errpipe_write) errpipe_write = os.dup(errpipe_write) for low_fd in low_fds_to_close: os.close(low_fd) try: try: # We must avoid complex work that could involve # malloc or free in the child process to avoid # potential deadlocks, thus we do all this here. # and pass it to fork_exec() if env is not None: env_list = [] for k, v in env.items(): k = os.fsencode(k) if b'=' in k: raise ValueError("illegal environment variable name") env_list.append(k + b'=' + os.fsencode(v)) else: env_list = None # Use execv instead of execve. executable = os.fsencode(executable) if os.path.dirname(executable): executable_list = (executable,) else: # This matches the behavior of os._execvpe(). executable_list = tuple( os.path.join(os.fsencode(dir), executable) for dir in os.get_exec_path(env)) fds_to_keep = set(pass_fds) fds_to_keep.add(errpipe_write) self.pid = _posixsubprocess.fork_exec( args, executable_list, close_fds, tuple(sorted(map(int, fds_to_keep))), cwd, env_list, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, errpipe_read, errpipe_write, restore_signals, start_new_session, gid, gids, uid, umask, preexec_fn) self._child_created = True finally: # be sure the FD is closed no matter what os.close(errpipe_write) self._close_pipe_fds(p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) # Wait for exec to fail or succeed; possibly raising an # exception (limited in size) errpipe_data = bytearray() while True: part = os.read(errpipe_read, 50000) errpipe_data += part if not part or len(errpipe_data) > 50000: break finally: # be sure the FD is closed no matter what os.close(errpipe_read) if errpipe_data: try: pid, sts = os.waitpid(self.pid, 0) if pid == self.pid: self._handle_exitstatus(sts) else: self.returncode = sys.maxsize except ChildProcessError: pass try: exception_name, hex_errno, err_msg = ( errpipe_data.split(b':', 2)) # The encoding here should match the encoding # written in by the subprocess implementations # like _posixsubprocess err_msg = err_msg.decode() except ValueError: exception_name = b'SubprocessError' hex_errno = b'0' err_msg = 'Bad exception data from child: {!r}'.format( bytes(errpipe_data)) child_exception_type = getattr( builtins, exception_name.decode('ascii'), SubprocessError) if issubclass(child_exception_type, OSError) and hex_errno: errno_num = int(hex_errno, 16) child_exec_never_called = (err_msg == "noexec") if child_exec_never_called: err_msg = "" # The error must be from chdir(cwd). err_filename = cwd else: err_filename = orig_executable if errno_num != 0: err_msg = os.strerror(errno_num) raise child_exception_type(errno_num, err_msg, err_filename) raise child_exception_type(err_msg) def _handle_exitstatus(self, sts, waitstatus_to_exitcode=os.waitstatus_to_exitcode, _WIFSTOPPED=os.WIFSTOPPED, _WSTOPSIG=os.WSTOPSIG): """All callers to this function MUST hold self._waitpid_lock.""" # This method is called (indirectly) by __del__, so it cannot # refer to anything outside of its local scope. if _WIFSTOPPED(sts): self.returncode = -_WSTOPSIG(sts) else: self.returncode = waitstatus_to_exitcode(sts) def _internal_poll(self, _deadstate=None, _waitpid=os.waitpid, _WNOHANG=os.WNOHANG, _ECHILD=errno.ECHILD): """Check if child process has terminated. Returns returncode attribute. This method is called by __del__, so it cannot reference anything outside of the local scope (nor can any methods it calls). """ if self.returncode is None: if not self._waitpid_lock.acquire(False): # Something else is busy calling waitpid. Don't allow two # at once. We know nothing yet. return None try: if self.returncode is not None: return self.returncode # Another thread waited. pid, sts = _waitpid(self.pid, _WNOHANG) if pid == self.pid: self._handle_exitstatus(sts) except OSError as e: if _deadstate is not None: self.returncode = _deadstate elif e.errno == _ECHILD: # This happens if SIGCLD is set to be ignored or # waiting for child processes has otherwise been # disabled for our process. This child is dead, we # can't get the status. # http://bugs.python.org/issue15756 self.returncode = 0 finally: self._waitpid_lock.release() return self.returncode def _try_wait(self, wait_flags): """All callers to this function MUST hold self._waitpid_lock.""" try: (pid, sts) = os.waitpid(self.pid, wait_flags) except ChildProcessError: # This happens if SIGCLD is set to be ignored or waiting # for child processes has otherwise been disabled for our # process. This child is dead, we can't get the status. pid = self.pid sts = 0 return (pid, sts) def _wait(self, timeout): """Internal implementation of wait() on POSIX.""" if self.returncode is not None: return self.returncode if timeout is not None: endtime = _time() + timeout # Enter a busy loop if we have a timeout. This busy loop was # cribbed from Lib/threading.py in Thread.wait() at r71065. delay = 0.0005 # 500 us -> initial delay of 1 ms while True: if self._waitpid_lock.acquire(False): try: if self.returncode is not None: break # Another thread waited. (pid, sts) = self._try_wait(os.WNOHANG) assert pid == self.pid or pid == 0 if pid == self.pid: self._handle_exitstatus(sts) break finally: self._waitpid_lock.release() remaining = self._remaining_time(endtime) if remaining <= 0: raise TimeoutExpired(self.args, timeout) delay = min(delay * 2, remaining, .05) time.sleep(delay) else: while self.returncode is None: with self._waitpid_lock: if self.returncode is not None: break # Another thread waited. (pid, sts) = self._try_wait(0) # Check the pid and loop as waitpid has been known to # return 0 even without WNOHANG in odd situations. # http://bugs.python.org/issue14396. if pid == self.pid: self._handle_exitstatus(sts) return self.returncode def _communicate(self, input, endtime, orig_timeout): if self.stdin and not self._communication_started: # Flush stdio buffer. This might block, if the user has # been writing to .stdin in an uncontrolled fashion. try: self.stdin.flush() except BrokenPipeError: pass # communicate() must ignore BrokenPipeError. if not input: try: self.stdin.close() except BrokenPipeError: pass # communicate() must ignore BrokenPipeError. stdout = None stderr = None # Only create this mapping if we haven't already. if not self._communication_started: self._fileobj2output = {} if self.stdout: self._fileobj2output[self.stdout] = [] if self.stderr: self._fileobj2output[self.stderr] = [] if self.stdout: stdout = self._fileobj2output[self.stdout] if self.stderr: stderr = self._fileobj2output[self.stderr] self._save_input(input) if self._input: input_view = memoryview(self._input) with _PopenSelector() as selector: if self.stdin and input: selector.register(self.stdin, selectors.EVENT_WRITE) if self.stdout and not self.stdout.closed: selector.register(self.stdout, selectors.EVENT_READ) if self.stderr and not self.stderr.closed: selector.register(self.stderr, selectors.EVENT_READ) while selector.get_map(): timeout = self._remaining_time(endtime) if timeout is not None and timeout < 0: self._check_timeout(endtime, orig_timeout, stdout, stderr, skip_check_and_raise=True) raise RuntimeError( # Impossible :) '_check_timeout(..., skip_check_and_raise=True) ' 'failed to raise TimeoutExpired.') ready = selector.select(timeout) self._check_timeout(endtime, orig_timeout, stdout, stderr) # XXX Rewrite these to use non-blocking I/O on the file # objects; they are no longer using C stdio! for key, events in ready: if key.fileobj is self.stdin: chunk = input_view[self._input_offset : self._input_offset + _PIPE_BUF] try: self._input_offset += os.write(key.fd, chunk) except BrokenPipeError: selector.unregister(key.fileobj) key.fileobj.close() else: if self._input_offset >= len(self._input): selector.unregister(key.fileobj) key.fileobj.close() elif key.fileobj in (self.stdout, self.stderr): data = os.read(key.fd, 32768) if not data: selector.unregister(key.fileobj) key.fileobj.close() self._fileobj2output[key.fileobj].append(data) self.wait(timeout=self._remaining_time(endtime)) # All data exchanged. Translate lists into strings. if stdout is not None: stdout = b''.join(stdout) if stderr is not None: stderr = b''.join(stderr) # Translate newlines, if requested. # This also turns bytes into strings. if self.text_mode: if stdout is not None: stdout = self._translate_newlines(stdout, self.stdout.encoding, self.stdout.errors) if stderr is not None: stderr = self._translate_newlines(stderr, self.stderr.encoding, self.stderr.errors) return (stdout, stderr) def _save_input(self, input): # This method is called from the _communicate_with_*() methods # so that if we time out while communicating, we can continue # sending input if we retry. if self.stdin and self._input is None: self._input_offset = 0 self._input = input if input is not None and self.text_mode: self._input = self._input.encode(self.stdin.encoding, self.stdin.errors) def send_signal(self, sig): """Send a signal to the process.""" # bpo-38630: Polling reduces the risk of sending a signal to the # wrong process if the process completed, the Popen.returncode # attribute is still None, and the pid has been reassigned # (recycled) to a new different process. This race condition can # happens in two cases. # # Case 1. Thread A calls Popen.poll(), thread B calls # Popen.send_signal(). In thread A, waitpid() succeed and returns # the exit status. Thread B calls kill() because poll() in thread A # did not set returncode yet. Calling poll() in thread B prevents # the race condition thanks to Popen._waitpid_lock. # # Case 2. waitpid(pid, 0) has been called directly, without # using Popen methods: returncode is still None is this case. # Calling Popen.poll() will set returncode to a default value, # since waitpid() fails with ProcessLookupError. self.poll() if self.returncode is not None: # Skip signalling a process that we know has already died. return # The race condition can still happen if the race condition # described above happens between the returncode test # and the kill() call. try: os.kill(self.pid, sig) except ProcessLookupError: # Supress the race condition error; bpo-40550. pass def terminate(self): """Terminate the process with SIGTERM """ self.send_signal(signal.SIGTERM) def kill(self): """Kill the process with SIGKILL """ self.send_signal(signal.SIGKILL)Instance variables
prop universal_newlines-
Expand source code
@property def universal_newlines(self): # universal_newlines as retained as an alias of text_mode for API # compatibility. bpo-31756 return self.text_mode
Methods
def communicate(self, input=None, timeout=None)-
Interact with process: Send data to stdin and close it. 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. communicate() returns a tuple (stdout, stderr).
By default, all communication is in bytes, and therefore any "input" should be bytes, and the (stdout, stderr) will be bytes. If in text mode (indicated by self.text_mode), any "input" should be a string, and (stdout, stderr) will be strings decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines.
def poll(self)-
Check if child process has terminated. Set and return returncode attribute.
def wait(self, timeout=None)-
Wait for child process to terminate; returns self.returncode.
def send_signal(self, sig)-
Send a signal to the process.
def terminate(self)-
Terminate the process with SIGTERM
def kill(self)-
Kill the process with SIGKILL