# subprocess - Subprocesses with accessible I/O streams # # For more information about this module, see PEP 324. # # Copyright (c) 2003-2005 by Peter Astrand # # Licensed to PSF under a Contributor Agreement. # See http://www.python.org/2.4/license for licensing details. r"""Subprocesses with accessible I/O streams This module allows you to spawn processes, connect to their input/output/error pipes, and obtain their return codes. For a complete description of this module see the Python documentation. Main API ======== run(...): Runs a command, waits for it to complete, then returns a CompletedProcess instance. Popen(...): A class for flexibly executing a command in a new process Constants --------- DEVNULL: Special value that indicates that os.devnull should be used PIPE: Special value that indicates a pipe should be created STDOUT: Special value that indicates that stderr should go to stdout Older API ========= call(...): Runs a command, waits for it to complete, then returns the return code. check_call(...): Same as call() but raises CalledProcessError() if return code is not 0 check_output(...): Same as check_call() but returns the contents of stdout instead of a return code getoutput(...): Runs a command in the shell, waits for it to complete, then returns the output getstatusoutput(...): Runs a command in the shell, waits for it to complete, then returns a (exitcode, output) tuple """ import sys import io import os import time import signal import builtins import warnings import errno from time import monotonic as _time from _subprocess import * # TODO: use these classes instead of the _subprocess ones # Exception classes used by this module. # class SubprocessError(Exception): pass # class CalledProcessError(SubprocessError): # """Raised when run() is called with check=True and the process # returns a non-zero exit status. # Attributes: # cmd, returncode, stdout, stderr, output # """ # def __init__(self, returncode, cmd, output=None, stderr=None): # self.returncode = returncode # self.cmd = cmd # self.output = output # self.stderr = stderr # def __str__(self): # if self.returncode and self.returncode < 0: # try: # return "Command '%s' died with %r." % ( # self.cmd, signal.Signals(-self.returncode)) # except ValueError: # return "Command '%s' died with unknown signal %d." % ( # self.cmd, -self.returncode) # else: # return "Command '%s' returned non-zero exit status %d." % ( # self.cmd, self.returncode) # @property # def stdout(self): # """Alias for output attribute, to match stderr""" # return self.output # @stdout.setter # def stdout(self, value): # # There's no obvious reason to set this, but allow it anyway so # # .stdout is a transparent alias for .output # self.output = value # class TimeoutExpired(SubprocessError): # """This exception is raised when the timeout expires while waiting for a # child process. # Attributes: # cmd, output, stdout, stderr, timeout # """ # def __init__(self, cmd, timeout, output=None, stderr=None): # self.cmd = cmd # self.timeout = timeout # self.output = output # self.stderr = stderr # def __str__(self): # return ("Command '%s' timed out after %s seconds" % # (self.cmd, self.timeout)) # @property # def stdout(self): # return self.output # @stdout.setter # def stdout(self, value): # # There's no obvious reason to set this, but allow it anyway so # # .stdout is a transparent alias for .output # self.output = value __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput", "getoutput", "check_output", "run", "CalledProcessError", "DEVNULL", "SubprocessError", "TimeoutExpired", "CompletedProcess"] # NOTE: We intentionally exclude list2cmdline as it is # considered an internal implementation detail. issue10838. # This lists holds Popen instances for which the underlying process had not # exited at the time its __del__ method got called: those processes are wait()ed # for synchronously from _cleanup() when a new Popen object is created, to avoid # zombie processes. _active = [] def _cleanup(): for inst in _active[:]: res = inst._internal_poll(_deadstate=sys.maxsize) if res is not None: try: _active.remove(inst) except ValueError: # This can happen if two threads create a new Popen instance. # It's harmless that it was already removed, so ignore. pass PIPE = -1 STDOUT = -2 DEVNULL = -3 # XXX This function is only used by multiprocessing and the test suite, # but it's here so that it can be imported when Python is compiled without # threads. def _optim_args_from_interpreter_flags(): """Return a list of command-line arguments reproducing the current optimization settings in sys.flags.""" args = [] value = sys.flags.optimize if value > 0: args.append('-' + 'O' * value) return args def _args_from_interpreter_flags(): """Return a list of command-line arguments reproducing the current settings in sys.flags, sys.warnoptions and sys._xoptions.""" flag_opt_map = { 'debug': 'd', # 'inspect': 'i', # 'interactive': 'i', 'dont_write_bytecode': 'B', 'no_user_site': 's', 'no_site': 'S', 'ignore_environment': 'E', 'verbose': 'v', 'bytes_warning': 'b', 'quiet': 'q', # -O is handled in _optim_args_from_interpreter_flags() } args = _optim_args_from_interpreter_flags() for flag, opt in flag_opt_map.items(): v = getattr(sys.flags, flag) if v > 0: args.append('-' + opt * v) # -W options warnopts = sys.warnoptions[:] bytes_warning = sys.flags.bytes_warning xoptions = getattr(sys, '_xoptions', {}) dev_mode = ('dev' in xoptions) if bytes_warning > 1: warnopts.remove("error::BytesWarning") elif bytes_warning: warnopts.remove("default::BytesWarning") if dev_mode: warnopts.remove('default') for opt in warnopts: args.append('-W' + opt) # -X options if dev_mode: args.extend(('-X', 'dev')) for opt in ('faulthandler', 'tracemalloc', 'importtime', 'showalloccount', 'showrefcount', 'utf8'): if opt in xoptions: value = xoptions[opt] if value is True: arg = opt else: arg = '%s=%s' % (opt, value) args.extend(('-X', arg)) return args def call(*popenargs, timeout=None, **kwargs): """Run command with arguments. Wait for command to complete or timeout, then return the returncode attribute. The arguments are the same as for the Popen constructor. Example: retcode = call(["ls", "-l"]) """ with Popen(*popenargs, **kwargs) as p: try: return p.wait(timeout=timeout) except: # Including KeyboardInterrupt, wait handled that. p.kill() # We don't call p.wait() again as p.__exit__ does that for us. raise def check_call(*popenargs, **kwargs): """Run command with arguments. Wait for command to complete. If the exit code was zero then return, otherwise raise CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute. The arguments are the same as for the call function. Example: check_call(["ls", "-l"]) """ retcode = call(*popenargs, **kwargs) if retcode: cmd = kwargs.get("args") if cmd is None: cmd = popenargs[0] raise CalledProcessError(retcode, cmd) return 0 def check_output(*popenargs, timeout=None, **kwargs): r"""Run command with arguments and return its output. If the exit code was non-zero it raises a CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute and output in the output attribute. The arguments are the same as for the Popen constructor. Example: >>> check_output(["ls", "-l", "/dev/null"]) b'crw-rw-rw- 1 root root 1, 3 Oct 18 2007 /dev/null\n' The stdout argument is not allowed as it is used internally. To capture standard error in the result, use stderr=STDOUT. >>> check_output(["/bin/sh", "-c", ... "ls -l non_existent_file ; exit 0"], ... stderr=STDOUT) b'ls: non_existent_file: No such file or directory\n' There is an additional optional argument, "input", allowing you to pass a string to the subprocess's stdin. If you use this argument you may not also use the Popen constructor's "stdin" argument, as it too will be used internally. Example: >>> check_output(["sed", "-e", "s/foo/bar/"], ... input=b"when in the course of fooman events\n") b'when in the course of barman events\n' By default, all communication is in bytes, and therefore any "input" should be bytes, and the return value wil be bytes. If in text mode, any "input" should be a string, and the return value will be a string 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 'stdout' in kwargs: raise ValueError('stdout argument not allowed, it will be overridden.') if 'input' in kwargs and kwargs['input'] is None: # Explicitly passing input=None was previously equivalent to passing an # empty string. That is maintained here for backwards compatibility. kwargs['input'] = '' if kwargs.get('universal_newlines', False) else b'' return run(*popenargs, stdout=PIPE, timeout=timeout, check=True, **kwargs).stdout class CompletedProcess(object): """A process that has finished running. This is returned by run(). Attributes: args: The list or str args passed to run(). returncode: The exit code of the process, negative for signals. stdout: The standard output (None if not captured). stderr: The standard error (None if not captured). """ def __init__(self, args, returncode, stdout=None, stderr=None): self.args = args self.returncode = returncode self.stdout = stdout self.stderr = stderr def __repr__(self): args = ['args={!r}'.format(self.args), 'returncode={!r}'.format(self.returncode)] if self.stdout is not None: args.append('stdout={!r}'.format(self.stdout)) if self.stderr is not None: args.append('stderr={!r}'.format(self.stderr)) return "{}({})".format(type(self).__name__, ', '.join(args)) def check_returncode(self): """Raise CalledProcessError if the exit code is non-zero.""" if self.returncode: raise CalledProcessError(self.returncode, self.args, self.stdout, self.stderr) def run(*popenargs, input=None, capture_output=False, timeout=None, check=False, **kwargs): """Run command with arguments and return a CompletedProcess instance. The returned instance will have attributes args, returncode, stdout and stderr. By default, stdout and stderr are not captured, and those attributes will be None. Pass stdout=PIPE and/or stderr=PIPE in order to capture them. If check is True and the exit code was non-zero, it raises a CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute, and output & stderr attributes if those streams were captured. If timeout is given, and the process takes too long, a TimeoutExpired exception will be raised. There is an optional argument "input", allowing you to pass bytes or a string to the subprocess's stdin. If you use this argument you may not also use the Popen constructor's "stdin" argument, as it will be used internally. By default, all communication is in bytes, and therefore any "input" should be bytes, and the stdout and stderr will be bytes. If in text mode, any "input" should be a string, and stdout and 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. The other arguments are the same as for the Popen constructor. """ if input is not None: if 'stdin' in kwargs: raise ValueError('stdin and input arguments may not both be used.') kwargs['stdin'] = PIPE if capture_output: if ('stdout' in kwargs) or ('stderr' in kwargs): raise ValueError('stdout and stderr arguments may not be used ' 'with capture_output.') kwargs['stdout'] = PIPE kwargs['stderr'] = PIPE with Popen(*popenargs, **kwargs) as process: try: stdout, stderr = process.communicate(input, timeout=timeout) except TimeoutExpired: process.kill() stdout, stderr = process.communicate() raise TimeoutExpired(process.args, timeout, output=stdout, stderr=stderr) except: # Including KeyboardInterrupt, communicate handled that. process.kill() # We don't call process.wait() as .__exit__ does that for us. raise retcode = process.poll() if check and retcode: raise CalledProcessError(retcode, process.args, output=stdout, stderr=stderr) return CompletedProcess(process.args, retcode, stdout, stderr) def list2cmdline(seq): """ Translate a sequence of arguments into a command line string, using the same rules as the MS C runtime: 1) Arguments are delimited by white space, which is either a space or a tab. 2) A string surrounded by double quotation marks is interpreted as a single argument, regardless of white space contained within. A quoted string can be embedded in an argument. 3) A double quotation mark preceded by a backslash is interpreted as a literal double quotation mark. 4) Backslashes are interpreted literally, unless they immediately precede a double quotation mark. 5) If backslashes immediately precede a double quotation mark, every pair of backslashes is interpreted as a literal backslash. If the number of backslashes is odd, the last backslash escapes the next double quotation mark as described in rule 3. """ # See # http://msdn.microsoft.com/en-us/library/17w5ykft.aspx # or search http://msdn.microsoft.com for # "Parsing C++ Command-Line Arguments" result = [] needquote = False for arg in seq: bs_buf = [] # Add a space to separate this argument from the others if result: result.append(' ') needquote = (" " in arg) or ("\t" in arg) or not arg if needquote: result.append('"') for c in arg: if c == '\\': # Don't know if we need to double yet. bs_buf.append(c) elif c == '"': # Double backslashes. result.append('\\' * len(bs_buf)*2) bs_buf = [] result.append('\\"') else: # Normal char if bs_buf: result.extend(bs_buf) bs_buf = [] result.append(c) # Add remaining backslashes, if any. if bs_buf: result.extend(bs_buf) if needquote: result.extend(bs_buf) result.append('"') return ''.join(result) # Various tools for executing commands and looking at their output and status. # def getstatusoutput(cmd): """Return (exitcode, output) of executing cmd in a shell. Execute the string 'cmd' in a shell with 'check_output' and return a 2-tuple (status, output). The locale encoding is used to decode the output and process newlines. A trailing newline is stripped from the output. The exit status for the command can be interpreted according to the rules for the function 'wait'. Example: >>> import subprocess >>> subprocess.getstatusoutput('ls /bin/ls') (0, '/bin/ls') >>> subprocess.getstatusoutput('cat /bin/junk') (1, 'cat: /bin/junk: No such file or directory') >>> subprocess.getstatusoutput('/bin/junk') (127, 'sh: /bin/junk: not found') >>> subprocess.getstatusoutput('/bin/kill $$') (-15, '') """ try: data = check_output(cmd, shell=True, text=True, stderr=STDOUT) exitcode = 0 except CalledProcessError as ex: data = ex.output exitcode = ex.returncode if data[-1:] == '\n': data = data[:-1] return exitcode, data def getoutput(cmd): """Return output (stdout or stderr) of executing cmd in a shell. Like getstatusoutput(), except the exit status is ignored and the return value is a string containing the command's output. Example: >>> import subprocess >>> subprocess.getoutput('ls /bin/ls') '/bin/ls' """ return getstatusoutput(cmd)[1]