1 # subprocess - Subprocesses with accessible I/O streams
3 # For more information about this module, see PEP 324.
5 # This module should remain compatible with Python 2.2, see PEP 291.
7 # Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se>
9 # Licensed to PSF under a Contributor Agreement.
10 # See http://www.python.org/2.4/license for licensing details.
12 r"""subprocess - Subprocesses with accessible I/O streams
14 This module allows you to spawn processes, connect to their
15 input/output/error pipes, and obtain their return codes. This module
16 intends to replace several other, older modules and functions, like:
24 Information about how the subprocess module can be used to replace these
25 modules and functions can be found below.
29 Using the subprocess module
30 ===========================
31 This module defines one class called Popen:
33 class Popen(args, bufsize=0, executable=None,
34 stdin=None, stdout=None, stderr=None,
35 preexec_fn=None, close_fds=False, shell=False,
36 cwd=None, env=None, universal_newlines=False,
37 startupinfo=None, creationflags=0):
42 args should be a string, or a sequence of program arguments. The
43 program to execute is normally the first item in the args sequence or
44 string, but can be explicitly set by using the executable argument.
46 On UNIX, with shell=False (default): In this case, the Popen class
47 uses os.execvp() to execute the child program. args should normally
48 be a sequence. A string will be treated as a sequence with the string
49 as the only item (the program to execute).
51 On UNIX, with shell=True: If args is a string, it specifies the
52 command string to execute through the shell. If args is a sequence,
53 the first item specifies the command string, and any additional items
54 will be treated as additional shell arguments.
56 On Windows: the Popen class uses CreateProcess() to execute the child
57 program, which operates on strings. If args is a sequence, it will be
58 converted to a string using the list2cmdline method. Please note that
59 not all MS Windows applications interpret the command line the same
60 way: The list2cmdline is designed for applications using the same
61 rules as the MS C runtime.
63 bufsize, if given, has the same meaning as the corresponding argument
64 to the built-in open() function: 0 means unbuffered, 1 means line
65 buffered, any other positive value means use a buffer of
66 (approximately) that size. A negative bufsize means to use the system
67 default, which usually means fully buffered. The default value for
68 bufsize is 0 (unbuffered).
70 stdin, stdout and stderr specify the executed programs' standard
71 input, standard output and standard error file handles, respectively.
72 Valid values are PIPE, an existing file descriptor (a positive
73 integer), an existing file object, and None. PIPE indicates that a
74 new pipe to the child should be created. With None, no redirection
75 will occur; the child's file handles will be inherited from the
76 parent. Additionally, stderr can be STDOUT, which indicates that the
77 stderr data from the applications should be captured into the same
78 file handle as for stdout.
80 If preexec_fn is set to a callable object, this object will be called
81 in the child process just before the child is executed.
83 If close_fds is true, all file descriptors except 0, 1 and 2 will be
84 closed before the child process is executed.
86 if shell is true, the specified command will be executed through the
89 If cwd is not None, the current directory will be changed to cwd
90 before the child is executed.
92 If env is not None, it defines the environment variables for the new
95 If universal_newlines is true, the file objects stdout and stderr are
96 opened as a text files, but lines may be terminated by any of '\n',
97 the Unix end-of-line convention, '\r', the Macintosh convention or
98 '\r\n', the Windows convention. All of these external representations
99 are seen as '\n' by the Python program. Note: This feature is only
100 available if Python is built with universal newline support (the
101 default). Also, the newlines attribute of the file objects stdout,
102 stdin and stderr are not updated by the communicate() method.
104 The startupinfo and creationflags, if given, will be passed to the
105 underlying CreateProcess() function. They can specify things such as
106 appearance of the main window and priority for the new process.
110 This module also defines two shortcut functions:
112 call(*popenargs, **kwargs):
113 Run command with arguments. Wait for command to complete, then
114 return the returncode attribute.
116 The arguments are the same as for the Popen constructor. Example:
118 retcode = call(["ls", "-l"])
120 check_call(*popenargs, **kwargs):
121 Run command with arguments. Wait for command to complete. If the
122 exit code was zero then return, otherwise raise
123 CalledProcessError. The CalledProcessError object will have the
124 return code in the returncode attribute.
126 The arguments are the same as for the Popen constructor. Example:
128 check_call(["ls", "-l"])
132 Exceptions raised in the child process, before the new program has
133 started to execute, will be re-raised in the parent. Additionally,
134 the exception object will have one extra attribute called
135 'child_traceback', which is a string containing traceback information
136 from the childs point of view.
138 The most common exception raised is OSError. This occurs, for
139 example, when trying to execute a non-existent file. Applications
140 should prepare for OSErrors.
142 A ValueError will be raised if Popen is called with invalid arguments.
144 check_call() will raise CalledProcessError, if the called process
145 returns a non-zero return code.
150 Unlike some other popen functions, this implementation will never call
151 /bin/sh implicitly. This means that all characters, including shell
152 metacharacters, can safely be passed to child processes.
157 Instances of the Popen class have the following methods:
160 Check if child process has terminated. Returns returncode
164 Wait for child process to terminate. Returns returncode attribute.
166 communicate(input=None)
167 Interact with process: Send data to stdin. Read data from stdout
168 and stderr, until end-of-file is reached. Wait for process to
169 terminate. The optional stdin argument should be a string to be
170 sent to the child process, or None, if no data should be sent to
173 communicate() returns a tuple (stdout, stderr).
175 Note: The data read is buffered in memory, so do not use this
176 method if the data size is large or unlimited.
178 The following attributes are also available:
181 If the stdin argument is PIPE, this attribute is a file object
182 that provides input to the child process. Otherwise, it is None.
185 If the stdout argument is PIPE, this attribute is a file object
186 that provides output from the child process. Otherwise, it is
190 If the stderr argument is PIPE, this attribute is file object that
191 provides error output from the child process. Otherwise, it is
195 The process ID of the child process.
198 The child return code. A None value indicates that the process
199 hasn't terminated yet. A negative value -N indicates that the
200 child was terminated by signal N (UNIX only).
203 Replacing older functions with the subprocess module
204 ====================================================
205 In this section, "a ==> b" means that b can be used as a replacement
208 Note: All functions in this section fail (more or less) silently if
209 the executed program cannot be found; this module raises an OSError
212 In the following examples, we assume that the subprocess module is
213 imported with "from subprocess import *".
216 Replacing /bin/sh shell backquote
217 ---------------------------------
220 output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]
223 Replacing shell pipe line
224 -------------------------
225 output=`dmesg | grep hda`
227 p1 = Popen(["dmesg"], stdout=PIPE)
228 p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
229 output = p2.communicate()[0]
232 Replacing os.system()
233 ---------------------
234 sts = os.system("mycmd" + " myarg")
236 p = Popen("mycmd" + " myarg", shell=True)
237 pid, sts = os.waitpid(p.pid, 0)
241 * Calling the program through the shell is usually not required.
243 * It's easier to look at the returncode attribute than the
246 A more real-world example would look like this:
249 retcode = call("mycmd" + " myarg", shell=True)
251 print >>sys.stderr, "Child was terminated by signal", -retcode
253 print >>sys.stderr, "Child returned", retcode
255 print >>sys.stderr, "Execution failed:", e
262 pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
264 pid = Popen(["/bin/mycmd", "myarg"]).pid
269 retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
271 retcode = call(["/bin/mycmd", "myarg"])
276 os.spawnvp(os.P_NOWAIT, path, args)
278 Popen([path] + args[1:])
283 os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
285 Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
290 pipe = os.popen(cmd, mode='r', bufsize)
292 pipe = Popen(cmd, shell=True, bufsize=bufsize, stdout=PIPE).stdout
294 pipe = os.popen(cmd, mode='w', bufsize)
296 pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin
299 (child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize)
301 p = Popen(cmd, shell=True, bufsize=bufsize,
302 stdin=PIPE, stdout=PIPE, close_fds=True)
303 (child_stdin, child_stdout) = (p.stdin, p.stdout)
308 child_stderr) = os.popen3(cmd, mode, bufsize)
310 p = Popen(cmd, shell=True, bufsize=bufsize,
311 stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
314 child_stderr) = (p.stdin, p.stdout, p.stderr)
317 (child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize)
319 p = Popen(cmd, shell=True, bufsize=bufsize,
320 stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
321 (child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout)
326 Note: If the cmd argument to popen2 functions is a string, the command
327 is executed through /bin/sh. If it is a list, the command is directly
330 (child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
332 p = Popen(["somestring"], shell=True, bufsize=bufsize
333 stdin=PIPE, stdout=PIPE, close_fds=True)
334 (child_stdout, child_stdin) = (p.stdout, p.stdin)
337 (child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
339 p = Popen(["mycmd", "myarg"], bufsize=bufsize,
340 stdin=PIPE, stdout=PIPE, close_fds=True)
341 (child_stdout, child_stdin) = (p.stdout, p.stdin)
343 The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
346 * subprocess.Popen raises an exception if the execution fails
347 * the capturestderr argument is replaced with the stderr argument.
348 * stdin=PIPE and stdout=PIPE must be specified.
349 * popen2 closes all filedescriptors by default, but you have to specify
350 close_fds=True with subprocess.Popen.
356 mswindows = (sys.platform == "win32")
362 # Exception classes used by this module.
363 class CalledProcessError(Exception):
364 """This exception is raised when a process run by check_call() returns
365 a non-zero exit status. The exit status will be stored in the
366 returncode attribute."""
367 def __init__(self, returncode, cmd):
368 self.returncode = returncode
371 return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
378 # SCons: the threading module is only used by the communicate()
379 # method, which we don't actually use, so don't worry if we
384 # Try to get _subprocess
385 from _subprocess import *
395 # If not there, then drop back to requiring pywin32
396 # TODO: Should this be wrapped in try as well? To notify user to install
397 # pywin32 ? With URL to it?
399 from win32api import GetStdHandle, STD_INPUT_HANDLE, \
400 STD_OUTPUT_HANDLE, STD_ERROR_HANDLE
401 from win32api import GetCurrentProcess, DuplicateHandle, \
402 GetModuleFileName, GetVersion
403 from win32con import DUPLICATE_SAME_ACCESS, SW_HIDE
404 from win32pipe import CreatePipe
405 from win32process import CreateProcess, STARTUPINFO, \
406 GetExitCodeProcess, STARTF_USESTDHANDLES, \
407 STARTF_USESHOWWINDOW, CREATE_NEW_CONSOLE
408 from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0
419 except AttributeError:
424 except AttributeError:
427 __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"]
430 MAXFD = os.sysconf("SC_OPEN_MAX")
431 except KeyboardInterrupt:
432 raise # SCons: don't swallow keyboard interrupts
436 # True/False does not exist on 2.2.0
447 return isinstance(obj, type(1))
448 def is_int_or_long(obj):
449 return type(obj) in (type(1), type(1L))
452 return isinstance(obj, int)
453 def is_int_or_long(obj):
454 return isinstance(obj, (int, long))
458 except AttributeError:
460 types.StringTypes = (str, unicode)
461 except AttributeError:
462 types.StringTypes = (str,)
464 return type(obj) in types.StringTypes
467 return isinstance(obj, types.StringTypes)
472 for inst in _active[:]:
473 if inst.poll(_deadstate=sys.maxsize) >= 0:
477 # This can happen if two threads create a new Popen instance.
478 # It's harmless that it was already removed, so ignore.
485 def call(*popenargs, **kwargs):
486 """Run command with arguments. Wait for command to complete, then
487 return the returncode attribute.
489 The arguments are the same as for the Popen constructor. Example:
491 retcode = call(["ls", "-l"])
493 return apply(Popen, popenargs, kwargs).wait()
496 def check_call(*popenargs, **kwargs):
497 """Run command with arguments. Wait for command to complete. If
498 the exit code was zero then return, otherwise raise
499 CalledProcessError. The CalledProcessError object will have the
500 return code in the returncode attribute.
502 The arguments are the same as for the Popen constructor. Example:
504 check_call(["ls", "-l"])
506 retcode = call(*popenargs, **kwargs)
507 cmd = kwargs.get("args")
511 raise CalledProcessError(retcode, cmd)
515 def list2cmdline(seq):
517 Translate a sequence of arguments into a command line
518 string, using the same rules as the MS C runtime:
520 1) Arguments are delimited by white space, which is either a
523 2) A string surrounded by double quotation marks is
524 interpreted as a single argument, regardless of white space
525 contained within. A quoted string can be embedded in an
528 3) A double quotation mark preceded by a backslash is
529 interpreted as a literal double quotation mark.
531 4) Backslashes are interpreted literally, unless they
532 immediately precede a double quotation mark.
534 5) If backslashes immediately precede a double quotation mark,
535 every pair of backslashes is interpreted as a literal
536 backslash. If the number of backslashes is odd, the last
537 backslash escapes the next double quotation mark as
542 # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
548 # Add a space to separate this argument from the others
552 needquote = (" " in arg) or ("\t" in arg)
558 # Don't know if we need to double yet.
562 result.append('\\' * len(bs_buf)*2)
568 result.extend(bs_buf)
572 # Add remaining backspaces, if any.
574 result.extend(bs_buf)
577 result.extend(bs_buf)
580 return ''.join(result)
590 def __init__(self, args, bufsize=0, executable=None,
591 stdin=None, stdout=None, stderr=None,
592 preexec_fn=None, close_fds=False, shell=False,
593 cwd=None, env=None, universal_newlines=False,
594 startupinfo=None, creationflags=0):
595 """Create new Popen instance."""
598 self._child_created = False
599 if not is_int_or_long(bufsize):
600 raise TypeError("bufsize must be an integer")
603 if preexec_fn is not None:
604 raise ValueError("preexec_fn is not supported on Windows "
607 raise ValueError("close_fds is not supported on Windows "
611 if startupinfo is not None:
612 raise ValueError("startupinfo is only supported on Windows "
614 if creationflags != 0:
615 raise ValueError("creationflags is only supported on Windows "
622 self.returncode = None
623 self.universal_newlines = universal_newlines
625 # Input and output objects. The general principle is like
630 # p2cwrite ---stdin---> p2cread
631 # c2pread <--stdout--- c2pwrite
632 # errread <--stderr--- errwrite
634 # On POSIX, the child objects are file descriptors. On
635 # Windows, these are Windows file handles. The parent objects
636 # are file descriptors on both platforms. The parent objects
637 # are None when not using PIPEs. The child objects are None
638 # when not redirecting.
642 errread, errwrite) = self._get_handles(stdin, stdout, stderr)
644 self._execute_child(args, executable, preexec_fn, close_fds,
645 cwd, env, universal_newlines,
646 startupinfo, creationflags, shell,
652 self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
654 if universal_newlines:
655 self.stdout = os.fdopen(c2pread, 'rU', bufsize)
657 self.stdout = os.fdopen(c2pread, 'rb', bufsize)
659 if universal_newlines:
660 self.stderr = os.fdopen(errread, 'rU', bufsize)
662 self.stderr = os.fdopen(errread, 'rb', bufsize)
665 def _translate_newlines(self, data):
666 data = data.replace("\r\n", "\n")
667 data = data.replace("\r", "\n")
672 if not self._child_created:
673 # We didn't get to successfully create a child process.
675 # In case the child hasn't been waited on, check if it's done.
676 self.poll(_deadstate=sys.maxsize)
677 if self.returncode is None and _active is not None:
678 # Child is still running, keep us alive until we can wait on it.
682 def communicate(self, input=None):
683 """Interact with process: Send data to stdin. Read data from
684 stdout and stderr, until end-of-file is reached. Wait for
685 process to terminate. The optional input argument should be a
686 string to be sent to the child process, or None, if no data
687 should be sent to the child.
689 communicate() returns a tuple (stdout, stderr)."""
691 # Optimization: If we are only using one pipe, or no pipe at
692 # all, using select() or threads is unnecessary.
693 if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
698 self.stdin.write(input)
701 stdout = self.stdout.read()
703 stderr = self.stderr.read()
705 return (stdout, stderr)
707 return self._communicate(input)
714 def _get_handles(self, stdin, stdout, stderr):
715 """Construct and return tupel with IO objects:
716 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
718 if stdin is None and stdout is None and stderr is None:
719 return (None, None, None, None, None, None)
721 p2cread, p2cwrite = None, None
722 c2pread, c2pwrite = None, None
723 errread, errwrite = None, None
726 p2cread = GetStdHandle(STD_INPUT_HANDLE)
728 p2cread, p2cwrite = CreatePipe(None, 0)
729 # Detach and turn into fd
730 p2cwrite = p2cwrite.Detach()
731 p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0)
733 p2cread = msvcrt.get_osfhandle(stdin)
735 # Assuming file-like object
736 p2cread = msvcrt.get_osfhandle(stdin.fileno())
737 p2cread = self._make_inheritable(p2cread)
740 c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE)
742 c2pread, c2pwrite = CreatePipe(None, 0)
743 # Detach and turn into fd
744 c2pread = c2pread.Detach()
745 c2pread = msvcrt.open_osfhandle(c2pread, 0)
747 c2pwrite = msvcrt.get_osfhandle(stdout)
749 # Assuming file-like object
750 c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
751 c2pwrite = self._make_inheritable(c2pwrite)
754 errwrite = GetStdHandle(STD_ERROR_HANDLE)
756 errread, errwrite = CreatePipe(None, 0)
757 # Detach and turn into fd
758 errread = errread.Detach()
759 errread = msvcrt.open_osfhandle(errread, 0)
760 elif stderr == STDOUT:
763 errwrite = msvcrt.get_osfhandle(stderr)
765 # Assuming file-like object
766 errwrite = msvcrt.get_osfhandle(stderr.fileno())
767 errwrite = self._make_inheritable(errwrite)
769 return (p2cread, p2cwrite,
774 def _make_inheritable(self, handle):
775 """Return a duplicate of handle, which is inheritable"""
776 return DuplicateHandle(GetCurrentProcess(), handle,
777 GetCurrentProcess(), 0, 1,
778 DUPLICATE_SAME_ACCESS)
781 def _find_w9xpopen(self):
782 """Find and return absolut path to w9xpopen.exe"""
783 w9xpopen = os.path.join(os.path.dirname(GetModuleFileName(0)),
785 if not os.path.exists(w9xpopen):
786 # Eeek - file-not-found - possibly an embedding
787 # situation - see if we can locate it in sys.exec_prefix
788 w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix),
790 if not os.path.exists(w9xpopen):
791 raise RuntimeError("Cannot locate w9xpopen.exe, which is "
792 "needed for Popen to work with your "
793 "shell or platform.")
797 def _execute_child(self, args, executable, preexec_fn, close_fds,
798 cwd, env, universal_newlines,
799 startupinfo, creationflags, shell,
803 """Execute program (MS Windows version)"""
805 if not isinstance(args, types.StringTypes):
806 args = list2cmdline(args)
808 # Process startup details
809 if startupinfo is None:
810 startupinfo = STARTUPINFO()
811 if None not in (p2cread, c2pwrite, errwrite):
812 startupinfo.dwFlags = startupinfo.dwFlags | STARTF_USESTDHANDLES
813 startupinfo.hStdInput = p2cread
814 startupinfo.hStdOutput = c2pwrite
815 startupinfo.hStdError = errwrite
818 startupinfo.dwFlags = startupinfo.dwFlags | STARTF_USESHOWWINDOW
819 startupinfo.wShowWindow = SW_HIDE
820 comspec = os.environ.get("COMSPEC", "cmd.exe")
821 args = comspec + " /c " + args
822 if (GetVersion() >= 0x80000000 or
823 os.path.basename(comspec).lower() == "command.com"):
824 # Win9x, or using command.com on NT. We need to
825 # use the w9xpopen intermediate program. For more
826 # information, see KB Q150956
827 # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
828 w9xpopen = self._find_w9xpopen()
829 args = '"%s" %s' % (w9xpopen, args)
830 # Not passing CREATE_NEW_CONSOLE has been known to
831 # cause random failures on win9x. Specifically a
832 # dialog: "Your program accessed mem currently in
833 # use at xxx" and a hopeful warning about the
834 # stability of your system. Cost is Ctrl+C wont
836 creationflags = creationflags | CREATE_NEW_CONSOLE
840 hp, ht, pid, tid = CreateProcess(executable, args,
841 # no special security
843 # must inherit handles to pass std
850 except pywintypes.error, e:
851 # Translate pywintypes.error to WindowsError, which is
852 # a subclass of OSError. FIXME: We should really
853 # translate errno using _sys_errlist (or simliar), but
854 # how can this be done from Python?
855 raise WindowsError(*e.args)
857 # Retain the process handle, but close the thread handle
858 self._child_created = True
863 # Child is launched. Close the parent's copy of those pipe
864 # handles that only the child should have open. You need
865 # to make sure that no handles to the write end of the
866 # output pipe are maintained in this process or else the
867 # pipe will not close when the child process exits and the
868 # ReadFile will hang.
869 if p2cread is not None:
871 if c2pwrite is not None:
873 if errwrite is not None:
877 def poll(self, _deadstate=None):
878 """Check if child process has terminated. Returns returncode
880 if self.returncode is None:
881 if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0:
882 self.returncode = GetExitCodeProcess(self._handle)
883 return self.returncode
887 """Wait for child process to terminate. Returns returncode
889 if self.returncode is None:
890 obj = WaitForSingleObject(self._handle, INFINITE)
891 self.returncode = GetExitCodeProcess(self._handle)
892 return self.returncode
895 def _readerthread(self, fh, buffer):
896 buffer.append(fh.read())
899 def _communicate(self, input):
900 stdout = None # Return
901 stderr = None # Return
905 stdout_thread = threading.Thread(target=self._readerthread,
906 args=(self.stdout, stdout))
907 stdout_thread.setDaemon(True)
908 stdout_thread.start()
911 stderr_thread = threading.Thread(target=self._readerthread,
912 args=(self.stderr, stderr))
913 stderr_thread.setDaemon(True)
914 stderr_thread.start()
917 if input is not None:
918 self.stdin.write(input)
926 # All data exchanged. Translate lists into strings.
927 if stdout is not None:
929 if stderr is not None:
932 # Translate newlines, if requested. We cannot let the file
933 # object do the translation: It is based on stdio, which is
934 # impossible to combine with select (unless forcing no
936 if self.universal_newlines and hasattr(file, 'newlines'):
938 stdout = self._translate_newlines(stdout)
940 stderr = self._translate_newlines(stderr)
943 return (stdout, stderr)
949 def _get_handles(self, stdin, stdout, stderr):
950 """Construct and return tupel with IO objects:
951 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
953 p2cread, p2cwrite = None, None
954 c2pread, c2pwrite = None, None
955 errread, errwrite = None, None
960 p2cread, p2cwrite = os.pipe()
964 # Assuming file-like object
965 p2cread = stdin.fileno()
970 c2pread, c2pwrite = os.pipe()
974 # Assuming file-like object
975 c2pwrite = stdout.fileno()
980 errread, errwrite = os.pipe()
981 elif stderr == STDOUT:
986 # Assuming file-like object
987 errwrite = stderr.fileno()
989 return (p2cread, p2cwrite,
994 def _set_cloexec_flag(self, fd):
996 cloexec_flag = fcntl.FD_CLOEXEC
997 except AttributeError:
1000 old = fcntl.fcntl(fd, fcntl.F_GETFD)
1001 fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag)
1004 def _close_fds(self, but):
1005 for i in xrange(3, MAXFD):
1010 except KeyboardInterrupt:
1011 raise # SCons: don't swallow keyboard interrupts
1016 def _execute_child(self, args, executable, preexec_fn, close_fds,
1017 cwd, env, universal_newlines,
1018 startupinfo, creationflags, shell,
1022 """Execute program (POSIX version)"""
1028 args = ["/bin/sh", "-c"] + args
1030 if executable is None:
1031 executable = args[0]
1033 # For transferring possible exec failure from child to parent
1034 # The first char specifies the exception type: 0 means
1035 # OSError, 1 means some other error.
1036 errpipe_read, errpipe_write = os.pipe()
1037 self._set_cloexec_flag(errpipe_write)
1039 self.pid = os.fork()
1040 self._child_created = True
1044 # Close parent's pipe ends
1051 os.close(errpipe_read)
1057 os.dup2(c2pwrite, 1)
1059 os.dup2(errwrite, 2)
1061 # Close pipe fds. Make sure we don't close the same
1062 # fd more than once, or standard fds.
1066 # Fall-back for earlier Python versions, so epydoc
1067 # can use this module directly to execute things.
1070 if c2pwrite and c2pwrite not in (p2cread,):
1072 if errwrite and errwrite not in (p2cread, c2pwrite):
1075 for fd in set((p2cread, c2pwrite, errwrite))-set((0,1,2)):
1078 # Close all other fds, if asked for
1080 self._close_fds(but=errpipe_write)
1089 os.execvp(executable, args)
1091 os.execvpe(executable, args, env)
1093 except KeyboardInterrupt:
1094 raise # SCons: don't swallow keyboard interrupts
1097 exc_type, exc_value, tb = sys.exc_info()
1098 # Save the traceback and attach it to the exception object
1099 exc_lines = traceback.format_exception(exc_type,
1102 exc_value.child_traceback = ''.join(exc_lines)
1103 os.write(errpipe_write, pickle.dumps(exc_value))
1105 # This exitcode won't be reported to applications, so it
1106 # really doesn't matter what we return.
1110 os.close(errpipe_write)
1111 if p2cread and p2cwrite:
1113 if c2pwrite and c2pread:
1115 if errwrite and errread:
1118 # Wait for exec to fail or succeed; possibly raising exception
1119 data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB
1120 os.close(errpipe_read)
1122 os.waitpid(self.pid, 0)
1123 child_exception = pickle.loads(data)
1124 raise child_exception
1127 def _handle_exitstatus(self, sts):
1128 if os.WIFSIGNALED(sts):
1129 self.returncode = -os.WTERMSIG(sts)
1130 elif os.WIFEXITED(sts):
1131 self.returncode = os.WEXITSTATUS(sts)
1133 # Should never happen
1134 raise RuntimeError("Unknown child exit status!")
1137 def poll(self, _deadstate=None):
1138 """Check if child process has terminated. Returns returncode
1140 if self.returncode is None:
1142 pid, sts = os.waitpid(self.pid, os.WNOHANG)
1144 self._handle_exitstatus(sts)
1146 if _deadstate is not None:
1147 self.returncode = _deadstate
1148 return self.returncode
1152 """Wait for child process to terminate. Returns returncode
1154 if self.returncode is None:
1155 pid, sts = os.waitpid(self.pid, 0)
1156 self._handle_exitstatus(sts)
1157 return self.returncode
1160 def _communicate(self, input):
1163 stdout = None # Return
1164 stderr = None # Return
1167 # Flush stdio buffer. This might block, if the user has
1168 # been writing to .stdin in an uncontrolled fashion.
1171 write_set.append(self.stdin)
1175 read_set.append(self.stdout)
1178 read_set.append(self.stderr)
1182 while read_set or write_set:
1183 rlist, wlist, xlist = select.select(read_set, write_set, [])
1185 if self.stdin in wlist:
1186 # When select has indicated that the file is writable,
1187 # we can write up to PIPE_BUF bytes without risk
1188 # blocking. POSIX defines PIPE_BUF >= 512
1189 bytes_written = os.write(self.stdin.fileno(), buffer(input, input_offset, 512))
1190 input_offset = input_offset + bytes_written
1191 if input_offset >= len(input):
1193 write_set.remove(self.stdin)
1195 if self.stdout in rlist:
1196 data = os.read(self.stdout.fileno(), 1024)
1199 read_set.remove(self.stdout)
1202 if self.stderr in rlist:
1203 data = os.read(self.stderr.fileno(), 1024)
1206 read_set.remove(self.stderr)
1209 # All data exchanged. Translate lists into strings.
1210 if stdout is not None:
1211 stdout = ''.join(stdout)
1212 if stderr is not None:
1213 stderr = ''.join(stderr)
1215 # Translate newlines, if requested. We cannot let the file
1216 # object do the translation: It is based on stdio, which is
1217 # impossible to combine with select (unless forcing no
1219 if self.universal_newlines and hasattr(file, 'newlines'):
1221 stdout = self._translate_newlines(stdout)
1223 stderr = self._translate_newlines(stderr)
1226 return (stdout, stderr)
1231 # Example 1: Simple redirection: Get process list
1233 plist = Popen(["ps"], stdout=PIPE).communicate()[0]
1234 print "Process list:"
1238 # Example 2: Change uid before executing child
1240 if os.getuid() == 0:
1241 p = Popen(["id"], preexec_fn=lambda: os.setuid(100))
1245 # Example 3: Connecting several subprocesses
1247 print "Looking for 'hda'..."
1248 p1 = Popen(["dmesg"], stdout=PIPE)
1249 p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
1250 print repr(p2.communicate()[0])
1253 # Example 4: Catch execution error
1256 print "Trying a weird file..."
1258 print Popen(["/this/path/does/not/exist"]).communicate()
1260 if e.errno == errno.ENOENT:
1261 print "The file didn't exist. I thought so..."
1262 print "Child traceback:"
1263 print e.child_traceback
1265 print "Error", e.errno
1267 sys.stderr.write( "Gosh. No error.\n" )
1270 def _demo_windows():
1272 # Example 1: Connecting several subprocesses
1274 print "Looking for 'PROMPT' in set output..."
1275 p1 = Popen("set", stdout=PIPE, shell=True)
1276 p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE)
1277 print repr(p2.communicate()[0])
1280 # Example 2: Simple execution of program
1282 print "Executing calc..."
1287 if __name__ == "__main__":
1295 # indent-tabs-mode:nil
1297 # vim: set expandtab tabstop=4 shiftwidth=4: