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 errno 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, which is a subclass of
145 OSError, if the called process 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 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(OSError):
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 errno attribute. This exception is a subclass of
372 if 0: # <-- change this to use pywin32 instead of the _subprocess driver
374 from win32api
import GetStdHandle
, STD_INPUT_HANDLE
, \
375 STD_OUTPUT_HANDLE
, STD_ERROR_HANDLE
376 from win32api
import GetCurrentProcess
, DuplicateHandle
, \
377 GetModuleFileName
, GetVersion
378 from win32con
import DUPLICATE_SAME_ACCESS
, SW_HIDE
379 from win32pipe
import CreatePipe
380 from win32process
import CreateProcess
, STARTUPINFO
, \
381 GetExitCodeProcess
, STARTF_USESTDHANDLES
, \
382 STARTF_USESHOWWINDOW
, CREATE_NEW_CONSOLE
383 from win32event
import WaitForSingleObject
, INFINITE
, WAIT_OBJECT_0
385 from _subprocess
import *
400 __all__
= ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"]
403 MAXFD
= os
.sysconf("SC_OPEN_MAX")
407 # True/False does not exist on 2.2.0
417 for inst
in _active
[:]:
418 if inst
.poll(_deadstate
=sys
.maxint
) >= 0:
422 # This can happen if two threads create a new Popen instance.
423 # It's harmless that it was already removed, so ignore.
430 def call(*popenargs
, **kwargs
):
431 """Run command with arguments. Wait for command to complete, then
432 return the returncode attribute.
434 The arguments are the same as for the Popen constructor. Example:
436 retcode = call(["ls", "-l"])
438 return Popen(*popenargs
, **kwargs
).wait()
441 def check_call(*popenargs
, **kwargs
):
442 """Run command with arguments. Wait for command to complete. If
443 the exit code was zero then return, otherwise raise
444 CalledProcessError. The CalledProcessError object will have the
445 return code in the errno attribute.
447 The arguments are the same as for the Popen constructor. Example:
449 check_call(["ls", "-l"])
451 retcode
= call(*popenargs
, **kwargs
)
452 cmd
= kwargs
.get("args")
456 raise CalledProcessError(retcode
, "Command %s returned non-zero exit status" % cmd
)
460 def list2cmdline(seq
):
462 Translate a sequence of arguments into a command line
463 string, using the same rules as the MS C runtime:
465 1) Arguments are delimited by white space, which is either a
468 2) A string surrounded by double quotation marks is
469 interpreted as a single argument, regardless of white space
470 contained within. A quoted string can be embedded in an
473 3) A double quotation mark preceded by a backslash is
474 interpreted as a literal double quotation mark.
476 4) Backslashes are interpreted literally, unless they
477 immediately precede a double quotation mark.
479 5) If backslashes immediately precede a double quotation mark,
480 every pair of backslashes is interpreted as a literal
481 backslash. If the number of backslashes is odd, the last
482 backslash escapes the next double quotation mark as
487 # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
493 # Add a space to separate this argument from the others
497 needquote
= (" " in arg
) or ("\t" in arg
)
503 # Don't know if we need to double yet.
507 result
.append('\\' * len(bs_buf
)*2)
513 result
.extend(bs_buf
)
517 # Add remaining backspaces, if any.
519 result
.extend(bs_buf
)
522 result
.extend(bs_buf
)
525 return ''.join(result
)
529 def __init__(self
, args
, bufsize
=0, executable
=None,
530 stdin
=None, stdout
=None, stderr
=None,
531 preexec_fn
=None, close_fds
=False, shell
=False,
532 cwd
=None, env
=None, universal_newlines
=False,
533 startupinfo
=None, creationflags
=0):
534 """Create new Popen instance."""
537 self
._child
_created
= False
538 if not isinstance(bufsize
, (int, long)):
539 raise TypeError("bufsize must be an integer")
542 if preexec_fn
is not None:
543 raise ValueError("preexec_fn is not supported on Windows "
546 raise ValueError("close_fds is not supported on Windows "
550 if startupinfo
is not None:
551 raise ValueError("startupinfo is only supported on Windows "
553 if creationflags
!= 0:
554 raise ValueError("creationflags is only supported on Windows "
561 self
.returncode
= None
562 self
.universal_newlines
= universal_newlines
564 # Input and output objects. The general principle is like
569 # p2cwrite ---stdin---> p2cread
570 # c2pread <--stdout--- c2pwrite
571 # errread <--stderr--- errwrite
573 # On POSIX, the child objects are file descriptors. On
574 # Windows, these are Windows file handles. The parent objects
575 # are file descriptors on both platforms. The parent objects
576 # are None when not using PIPEs. The child objects are None
577 # when not redirecting.
581 errread
, errwrite
) = self
._get
_handles
(stdin
, stdout
, stderr
)
583 self
._execute
_child
(args
, executable
, preexec_fn
, close_fds
,
584 cwd
, env
, universal_newlines
,
585 startupinfo
, creationflags
, shell
,
591 self
.stdin
= os
.fdopen(p2cwrite
, 'wb', bufsize
)
593 if universal_newlines
:
594 self
.stdout
= os
.fdopen(c2pread
, 'rU', bufsize
)
596 self
.stdout
= os
.fdopen(c2pread
, 'rb', bufsize
)
598 if universal_newlines
:
599 self
.stderr
= os
.fdopen(errread
, 'rU', bufsize
)
601 self
.stderr
= os
.fdopen(errread
, 'rb', bufsize
)
604 def _translate_newlines(self
, data
):
605 data
= data
.replace("\r\n", "\n")
606 data
= data
.replace("\r", "\n")
611 if not self
._child
_created
:
612 # We didn't get to successfully create a child process.
614 # In case the child hasn't been waited on, check if it's done.
615 self
.poll(_deadstate
=sys
.maxint
)
616 if self
.returncode
is None:
617 # Child is still running, keep us alive until we can wait on it.
621 def communicate(self
, input=None):
622 """Interact with process: Send data to stdin. Read data from
623 stdout and stderr, until end-of-file is reached. Wait for
624 process to terminate. The optional input argument should be a
625 string to be sent to the child process, or None, if no data
626 should be sent to the child.
628 communicate() returns a tuple (stdout, stderr)."""
630 # Optimization: If we are only using one pipe, or no pipe at
631 # all, using select() or threads is unnecessary.
632 if [self
.stdin
, self
.stdout
, self
.stderr
].count(None) >= 2:
637 self
.stdin
.write(input)
640 stdout
= self
.stdout
.read()
642 stderr
= self
.stderr
.read()
644 return (stdout
, stderr
)
646 return self
._communicate
(input)
653 def _get_handles(self
, stdin
, stdout
, stderr
):
654 """Construct and return tupel with IO objects:
655 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
657 if stdin
is None and stdout
is None and stderr
is None:
658 return (None, None, None, None, None, None)
660 p2cread
, p2cwrite
= None, None
661 c2pread
, c2pwrite
= None, None
662 errread
, errwrite
= None, None
665 p2cread
= GetStdHandle(STD_INPUT_HANDLE
)
667 p2cread
, p2cwrite
= CreatePipe(None, 0)
668 # Detach and turn into fd
669 p2cwrite
= p2cwrite
.Detach()
670 p2cwrite
= msvcrt
.open_osfhandle(p2cwrite
, 0)
671 elif isinstance(stdin
, int):
672 p2cread
= msvcrt
.get_osfhandle(stdin
)
674 # Assuming file-like object
675 p2cread
= msvcrt
.get_osfhandle(stdin
.fileno())
676 p2cread
= self
._make
_inheritable
(p2cread
)
679 c2pwrite
= GetStdHandle(STD_OUTPUT_HANDLE
)
681 c2pread
, c2pwrite
= CreatePipe(None, 0)
682 # Detach and turn into fd
683 c2pread
= c2pread
.Detach()
684 c2pread
= msvcrt
.open_osfhandle(c2pread
, 0)
685 elif isinstance(stdout
, int):
686 c2pwrite
= msvcrt
.get_osfhandle(stdout
)
688 # Assuming file-like object
689 c2pwrite
= msvcrt
.get_osfhandle(stdout
.fileno())
690 c2pwrite
= self
._make
_inheritable
(c2pwrite
)
693 errwrite
= GetStdHandle(STD_ERROR_HANDLE
)
695 errread
, errwrite
= CreatePipe(None, 0)
696 # Detach and turn into fd
697 errread
= errread
.Detach()
698 errread
= msvcrt
.open_osfhandle(errread
, 0)
699 elif stderr
== STDOUT
:
701 elif isinstance(stderr
, int):
702 errwrite
= msvcrt
.get_osfhandle(stderr
)
704 # Assuming file-like object
705 errwrite
= msvcrt
.get_osfhandle(stderr
.fileno())
706 errwrite
= self
._make
_inheritable
(errwrite
)
708 return (p2cread
, p2cwrite
,
713 def _make_inheritable(self
, handle
):
714 """Return a duplicate of handle, which is inheritable"""
715 return DuplicateHandle(GetCurrentProcess(), handle
,
716 GetCurrentProcess(), 0, 1,
717 DUPLICATE_SAME_ACCESS
)
720 def _find_w9xpopen(self
):
721 """Find and return absolut path to w9xpopen.exe"""
722 w9xpopen
= os
.path
.join(os
.path
.dirname(GetModuleFileName(0)),
724 if not os
.path
.exists(w9xpopen
):
725 # Eeek - file-not-found - possibly an embedding
726 # situation - see if we can locate it in sys.exec_prefix
727 w9xpopen
= os
.path
.join(os
.path
.dirname(sys
.exec_prefix
),
729 if not os
.path
.exists(w9xpopen
):
730 raise RuntimeError("Cannot locate w9xpopen.exe, which is "
731 "needed for Popen to work with your "
732 "shell or platform.")
736 def _execute_child(self
, args
, executable
, preexec_fn
, close_fds
,
737 cwd
, env
, universal_newlines
,
738 startupinfo
, creationflags
, shell
,
742 """Execute program (MS Windows version)"""
744 if not isinstance(args
, types
.StringTypes
):
745 args
= list2cmdline(args
)
747 # Process startup details
748 if startupinfo
is None:
749 startupinfo
= STARTUPINFO()
750 if None not in (p2cread
, c2pwrite
, errwrite
):
751 startupinfo
.dwFlags |
= STARTF_USESTDHANDLES
752 startupinfo
.hStdInput
= p2cread
753 startupinfo
.hStdOutput
= c2pwrite
754 startupinfo
.hStdError
= errwrite
757 startupinfo
.dwFlags |
= STARTF_USESHOWWINDOW
758 startupinfo
.wShowWindow
= SW_HIDE
759 comspec
= os
.environ
.get("COMSPEC", "cmd.exe")
760 args
= comspec
+ " /c " + args
761 if (GetVersion() >= 0x80000000L
or
762 os
.path
.basename(comspec
).lower() == "command.com"):
763 # Win9x, or using command.com on NT. We need to
764 # use the w9xpopen intermediate program. For more
765 # information, see KB Q150956
766 # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
767 w9xpopen
= self
._find
_w
9xpopen
()
768 args
= '"%s" %s' % (w9xpopen
, args
)
769 # Not passing CREATE_NEW_CONSOLE has been known to
770 # cause random failures on win9x. Specifically a
771 # dialog: "Your program accessed mem currently in
772 # use at xxx" and a hopeful warning about the
773 # stability of your system. Cost is Ctrl+C wont
775 creationflags |
= CREATE_NEW_CONSOLE
779 hp
, ht
, pid
, tid
= CreateProcess(executable
, args
,
780 # no special security
782 # must inherit handles to pass std
789 except pywintypes
.error
, e
:
790 # Translate pywintypes.error to WindowsError, which is
791 # a subclass of OSError. FIXME: We should really
792 # translate errno using _sys_errlist (or simliar), but
793 # how can this be done from Python?
794 raise WindowsError(*e
.args
)
796 # Retain the process handle, but close the thread handle
797 self
._child
_created
= True
802 # Child is launched. Close the parent's copy of those pipe
803 # handles that only the child should have open. You need
804 # to make sure that no handles to the write end of the
805 # output pipe are maintained in this process or else the
806 # pipe will not close when the child process exits and the
807 # ReadFile will hang.
808 if p2cread
is not None:
810 if c2pwrite
is not None:
812 if errwrite
is not None:
816 def poll(self
, _deadstate
=None):
817 """Check if child process has terminated. Returns returncode
819 if self
.returncode
is None:
820 if WaitForSingleObject(self
._handle
, 0) == WAIT_OBJECT_0
:
821 self
.returncode
= GetExitCodeProcess(self
._handle
)
822 return self
.returncode
826 """Wait for child process to terminate. Returns returncode
828 if self
.returncode
is None:
829 obj
= WaitForSingleObject(self
._handle
, INFINITE
)
830 self
.returncode
= GetExitCodeProcess(self
._handle
)
831 return self
.returncode
834 def _readerthread(self
, fh
, buffer):
835 buffer.append(fh
.read())
838 def _communicate(self
, input):
839 stdout
= None # Return
840 stderr
= None # Return
844 stdout_thread
= threading
.Thread(target
=self
._readerthread
,
845 args
=(self
.stdout
, stdout
))
846 stdout_thread
.setDaemon(True)
847 stdout_thread
.start()
850 stderr_thread
= threading
.Thread(target
=self
._readerthread
,
851 args
=(self
.stderr
, stderr
))
852 stderr_thread
.setDaemon(True)
853 stderr_thread
.start()
856 if input is not None:
857 self
.stdin
.write(input)
865 # All data exchanged. Translate lists into strings.
866 if stdout
is not None:
868 if stderr
is not None:
871 # Translate newlines, if requested. We cannot let the file
872 # object do the translation: It is based on stdio, which is
873 # impossible to combine with select (unless forcing no
875 if self
.universal_newlines
and hasattr(file, 'newlines'):
877 stdout
= self
._translate
_newlines
(stdout
)
879 stderr
= self
._translate
_newlines
(stderr
)
882 return (stdout
, stderr
)
888 def _get_handles(self
, stdin
, stdout
, stderr
):
889 """Construct and return tupel with IO objects:
890 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
892 p2cread
, p2cwrite
= None, None
893 c2pread
, c2pwrite
= None, None
894 errread
, errwrite
= None, None
899 p2cread
, p2cwrite
= os
.pipe()
900 elif isinstance(stdin
, int):
903 # Assuming file-like object
904 p2cread
= stdin
.fileno()
909 c2pread
, c2pwrite
= os
.pipe()
910 elif isinstance(stdout
, int):
913 # Assuming file-like object
914 c2pwrite
= stdout
.fileno()
919 errread
, errwrite
= os
.pipe()
920 elif stderr
== STDOUT
:
922 elif isinstance(stderr
, int):
925 # Assuming file-like object
926 errwrite
= stderr
.fileno()
928 return (p2cread
, p2cwrite
,
933 def _set_cloexec_flag(self
, fd
):
935 cloexec_flag
= fcntl
.FD_CLOEXEC
936 except AttributeError:
939 old
= fcntl
.fcntl(fd
, fcntl
.F_GETFD
)
940 fcntl
.fcntl(fd
, fcntl
.F_SETFD
, old | cloexec_flag
)
943 def _close_fds(self
, but
):
944 for i
in range(3, MAXFD
):
953 def _execute_child(self
, args
, executable
, preexec_fn
, close_fds
,
954 cwd
, env
, universal_newlines
,
955 startupinfo
, creationflags
, shell
,
959 """Execute program (POSIX version)"""
961 if isinstance(args
, types
.StringTypes
):
965 args
= ["/bin/sh", "-c"] + args
967 if executable
is None:
970 # For transferring possible exec failure from child to parent
971 # The first char specifies the exception type: 0 means
972 # OSError, 1 means some other error.
973 errpipe_read
, errpipe_write
= os
.pipe()
974 self
._set
_cloexec
_flag
(errpipe_write
)
977 self
._child
_created
= True
981 # Close parent's pipe ends
988 os
.close(errpipe_read
)
998 # Close pipe fds. Make sure we doesn't close the same
1002 if c2pwrite
and c2pwrite
not in (p2cread
,):
1004 if errwrite
and errwrite
not in (p2cread
, c2pwrite
):
1007 # Close all other fds, if asked for
1009 self
._close
_fds
(but
=errpipe_write
)
1018 os
.execvp(executable
, args
)
1020 os
.execvpe(executable
, args
, env
)
1023 exc_type
, exc_value
, tb
= sys
.exc_info()
1024 # Save the traceback and attach it to the exception object
1025 exc_lines
= traceback
.format_exception(exc_type
,
1028 exc_value
.child_traceback
= ''.join(exc_lines
)
1029 os
.write(errpipe_write
, pickle
.dumps(exc_value
))
1031 # This exitcode won't be reported to applications, so it
1032 # really doesn't matter what we return.
1036 os
.close(errpipe_write
)
1037 if p2cread
and p2cwrite
:
1039 if c2pwrite
and c2pread
:
1041 if errwrite
and errread
:
1044 # Wait for exec to fail or succeed; possibly raising exception
1045 data
= os
.read(errpipe_read
, 1048576) # Exceptions limited to 1 MB
1046 os
.close(errpipe_read
)
1048 os
.waitpid(self
.pid
, 0)
1049 child_exception
= pickle
.loads(data
)
1050 raise child_exception
1053 def _handle_exitstatus(self
, sts
):
1054 if os
.WIFSIGNALED(sts
):
1055 self
.returncode
= -os
.WTERMSIG(sts
)
1056 elif os
.WIFEXITED(sts
):
1057 self
.returncode
= os
.WEXITSTATUS(sts
)
1059 # Should never happen
1060 raise RuntimeError("Unknown child exit status!")
1063 def poll(self
, _deadstate
=None):
1064 """Check if child process has terminated. Returns returncode
1066 if self
.returncode
is None:
1068 pid
, sts
= os
.waitpid(self
.pid
, os
.WNOHANG
)
1070 self
._handle
_exitstatus
(sts
)
1072 if _deadstate
is not None:
1073 self
.returncode
= _deadstate
1074 return self
.returncode
1078 """Wait for child process to terminate. Returns returncode
1080 if self
.returncode
is None:
1081 pid
, sts
= os
.waitpid(self
.pid
, 0)
1082 self
._handle
_exitstatus
(sts
)
1083 return self
.returncode
1086 def _communicate(self
, input):
1089 stdout
= None # Return
1090 stderr
= None # Return
1093 # Flush stdio buffer. This might block, if the user has
1094 # been writing to .stdin in an uncontrolled fashion.
1097 write_set
.append(self
.stdin
)
1101 read_set
.append(self
.stdout
)
1104 read_set
.append(self
.stderr
)
1107 while read_set
or write_set
:
1108 rlist
, wlist
, xlist
= select
.select(read_set
, write_set
, [])
1110 if self
.stdin
in wlist
:
1111 # When select has indicated that the file is writable,
1112 # we can write up to PIPE_BUF bytes without risk
1113 # blocking. POSIX defines PIPE_BUF >= 512
1114 bytes_written
= os
.write(self
.stdin
.fileno(), input[:512])
1115 input = input[bytes_written
:]
1118 write_set
.remove(self
.stdin
)
1120 if self
.stdout
in rlist
:
1121 data
= os
.read(self
.stdout
.fileno(), 1024)
1124 read_set
.remove(self
.stdout
)
1127 if self
.stderr
in rlist
:
1128 data
= os
.read(self
.stderr
.fileno(), 1024)
1131 read_set
.remove(self
.stderr
)
1134 # All data exchanged. Translate lists into strings.
1135 if stdout
is not None:
1136 stdout
= ''.join(stdout
)
1137 if stderr
is not None:
1138 stderr
= ''.join(stderr
)
1140 # Translate newlines, if requested. We cannot let the file
1141 # object do the translation: It is based on stdio, which is
1142 # impossible to combine with select (unless forcing no
1144 if self
.universal_newlines
and hasattr(file, 'newlines'):
1146 stdout
= self
._translate
_newlines
(stdout
)
1148 stderr
= self
._translate
_newlines
(stderr
)
1151 return (stdout
, stderr
)
1156 # Example 1: Simple redirection: Get process list
1158 plist
= Popen(["ps"], stdout
=PIPE
).communicate()[0]
1159 print "Process list:"
1163 # Example 2: Change uid before executing child
1165 if os
.getuid() == 0:
1166 p
= Popen(["id"], preexec_fn
=lambda: os
.setuid(100))
1170 # Example 3: Connecting several subprocesses
1172 print "Looking for 'hda'..."
1173 p1
= Popen(["dmesg"], stdout
=PIPE
)
1174 p2
= Popen(["grep", "hda"], stdin
=p1
.stdout
, stdout
=PIPE
)
1175 print repr(p2
.communicate()[0])
1178 # Example 4: Catch execution error
1181 print "Trying a weird file..."
1183 print Popen(["/this/path/does/not/exist"]).communicate()
1185 if e
.errno
== errno
.ENOENT
:
1186 print "The file didn't exist. I thought so..."
1187 print "Child traceback:"
1188 print e
.child_traceback
1190 print "Error", e
.errno
1192 print >>sys
.stderr
, "Gosh. No error."
1195 def _demo_windows():
1197 # Example 1: Connecting several subprocesses
1199 print "Looking for 'PROMPT' in set output..."
1200 p1
= Popen("set", stdout
=PIPE
, shell
=True)
1201 p2
= Popen('find "PROMPT"', stdin
=p1
.stdout
, stdout
=PIPE
)
1202 print repr(p2
.communicate()[0])
1205 # Example 2: Simple execution of program
1207 print "Executing calc..."
1212 if __name__
== "__main__":