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 *
399 __all__
= ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"]
402 MAXFD
= os
.sysconf("SC_OPEN_MAX")
406 # True/False does not exist on 2.2.0
416 for inst
in _active
[:]:
423 def call(*popenargs
, **kwargs
):
424 """Run command with arguments. Wait for command to complete, then
425 return the returncode attribute.
427 The arguments are the same as for the Popen constructor. Example:
429 retcode = call(["ls", "-l"])
431 return Popen(*popenargs
, **kwargs
).wait()
434 def check_call(*popenargs
, **kwargs
):
435 """Run command with arguments. Wait for command to complete. If
436 the exit code was zero then return, otherwise raise
437 CalledProcessError. The CalledProcessError object will have the
438 return code in the errno attribute.
440 The arguments are the same as for the Popen constructor. Example:
442 check_call(["ls", "-l"])
444 retcode
= call(*popenargs
, **kwargs
)
445 cmd
= kwargs
.get("args")
449 raise CalledProcessError(retcode
, "Command %s returned non-zero exit status" % cmd
)
453 def list2cmdline(seq
):
455 Translate a sequence of arguments into a command line
456 string, using the same rules as the MS C runtime:
458 1) Arguments are delimited by white space, which is either a
461 2) A string surrounded by double quotation marks is
462 interpreted as a single argument, regardless of white space
463 contained within. A quoted string can be embedded in an
466 3) A double quotation mark preceded by a backslash is
467 interpreted as a literal double quotation mark.
469 4) Backslashes are interpreted literally, unless they
470 immediately precede a double quotation mark.
472 5) If backslashes immediately precede a double quotation mark,
473 every pair of backslashes is interpreted as a literal
474 backslash. If the number of backslashes is odd, the last
475 backslash escapes the next double quotation mark as
480 # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
486 # Add a space to separate this argument from the others
490 needquote
= (" " in arg
) or ("\t" in arg
)
496 # Don't know if we need to double yet.
500 result
.append('\\' * len(bs_buf
)*2)
506 result
.extend(bs_buf
)
510 # Add remaining backspaces, if any.
512 result
.extend(bs_buf
)
515 result
.extend(bs_buf
)
518 return ''.join(result
)
522 def __init__(self
, args
, bufsize
=0, executable
=None,
523 stdin
=None, stdout
=None, stderr
=None,
524 preexec_fn
=None, close_fds
=False, shell
=False,
525 cwd
=None, env
=None, universal_newlines
=False,
526 startupinfo
=None, creationflags
=0):
527 """Create new Popen instance."""
530 if not isinstance(bufsize
, (int, long)):
531 raise TypeError("bufsize must be an integer")
534 if preexec_fn
is not None:
535 raise ValueError("preexec_fn is not supported on Windows "
538 raise ValueError("close_fds is not supported on Windows "
542 if startupinfo
is not None:
543 raise ValueError("startupinfo is only supported on Windows "
545 if creationflags
!= 0:
546 raise ValueError("creationflags is only supported on Windows "
553 self
.returncode
= None
554 self
.universal_newlines
= universal_newlines
556 # Input and output objects. The general principle is like
561 # p2cwrite ---stdin---> p2cread
562 # c2pread <--stdout--- c2pwrite
563 # errread <--stderr--- errwrite
565 # On POSIX, the child objects are file descriptors. On
566 # Windows, these are Windows file handles. The parent objects
567 # are file descriptors on both platforms. The parent objects
568 # are None when not using PIPEs. The child objects are None
569 # when not redirecting.
573 errread
, errwrite
) = self
._get
_handles
(stdin
, stdout
, stderr
)
575 self
._execute
_child
(args
, executable
, preexec_fn
, close_fds
,
576 cwd
, env
, universal_newlines
,
577 startupinfo
, creationflags
, shell
,
583 self
.stdin
= os
.fdopen(p2cwrite
, 'wb', bufsize
)
585 if universal_newlines
:
586 self
.stdout
= os
.fdopen(c2pread
, 'rU', bufsize
)
588 self
.stdout
= os
.fdopen(c2pread
, 'rb', bufsize
)
590 if universal_newlines
:
591 self
.stderr
= os
.fdopen(errread
, 'rU', bufsize
)
593 self
.stderr
= os
.fdopen(errread
, 'rb', bufsize
)
598 def _translate_newlines(self
, data
):
599 data
= data
.replace("\r\n", "\n")
600 data
= data
.replace("\r", "\n")
603 def communicate(self
, input=None):
604 """Interact with process: Send data to stdin. Read data from
605 stdout and stderr, until end-of-file is reached. Wait for
606 process to terminate. The optional input argument should be a
607 string to be sent to the child process, or None, if no data
608 should be sent to the child.
610 communicate() returns a tuple (stdout, stderr)."""
612 # Optimization: If we are only using one pipe, or no pipe at
613 # all, using select() or threads is unnecessary.
614 if [self
.stdin
, self
.stdout
, self
.stderr
].count(None) >= 2:
619 self
.stdin
.write(input)
622 stdout
= self
.stdout
.read()
624 stderr
= self
.stderr
.read()
626 return (stdout
, stderr
)
628 return self
._communicate
(input)
635 def _get_handles(self
, stdin
, stdout
, stderr
):
636 """Construct and return tupel with IO objects:
637 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
639 if stdin
is None and stdout
is None and stderr
is None:
640 return (None, None, None, None, None, None)
642 p2cread
, p2cwrite
= None, None
643 c2pread
, c2pwrite
= None, None
644 errread
, errwrite
= None, None
647 p2cread
= GetStdHandle(STD_INPUT_HANDLE
)
649 p2cread
, p2cwrite
= CreatePipe(None, 0)
650 # Detach and turn into fd
651 p2cwrite
= p2cwrite
.Detach()
652 p2cwrite
= msvcrt
.open_osfhandle(p2cwrite
, 0)
653 elif isinstance(stdin
, int):
654 p2cread
= msvcrt
.get_osfhandle(stdin
)
656 # Assuming file-like object
657 p2cread
= msvcrt
.get_osfhandle(stdin
.fileno())
658 p2cread
= self
._make
_inheritable
(p2cread
)
661 c2pwrite
= GetStdHandle(STD_OUTPUT_HANDLE
)
663 c2pread
, c2pwrite
= CreatePipe(None, 0)
664 # Detach and turn into fd
665 c2pread
= c2pread
.Detach()
666 c2pread
= msvcrt
.open_osfhandle(c2pread
, 0)
667 elif isinstance(stdout
, int):
668 c2pwrite
= msvcrt
.get_osfhandle(stdout
)
670 # Assuming file-like object
671 c2pwrite
= msvcrt
.get_osfhandle(stdout
.fileno())
672 c2pwrite
= self
._make
_inheritable
(c2pwrite
)
675 errwrite
= GetStdHandle(STD_ERROR_HANDLE
)
677 errread
, errwrite
= CreatePipe(None, 0)
678 # Detach and turn into fd
679 errread
= errread
.Detach()
680 errread
= msvcrt
.open_osfhandle(errread
, 0)
681 elif stderr
== STDOUT
:
683 elif isinstance(stderr
, int):
684 errwrite
= msvcrt
.get_osfhandle(stderr
)
686 # Assuming file-like object
687 errwrite
= msvcrt
.get_osfhandle(stderr
.fileno())
688 errwrite
= self
._make
_inheritable
(errwrite
)
690 return (p2cread
, p2cwrite
,
695 def _make_inheritable(self
, handle
):
696 """Return a duplicate of handle, which is inheritable"""
697 return DuplicateHandle(GetCurrentProcess(), handle
,
698 GetCurrentProcess(), 0, 1,
699 DUPLICATE_SAME_ACCESS
)
702 def _find_w9xpopen(self
):
703 """Find and return absolut path to w9xpopen.exe"""
704 w9xpopen
= os
.path
.join(os
.path
.dirname(GetModuleFileName(0)),
706 if not os
.path
.exists(w9xpopen
):
707 # Eeek - file-not-found - possibly an embedding
708 # situation - see if we can locate it in sys.exec_prefix
709 w9xpopen
= os
.path
.join(os
.path
.dirname(sys
.exec_prefix
),
711 if not os
.path
.exists(w9xpopen
):
712 raise RuntimeError("Cannot locate w9xpopen.exe, which is "
713 "needed for Popen to work with your "
714 "shell or platform.")
718 def _execute_child(self
, args
, executable
, preexec_fn
, close_fds
,
719 cwd
, env
, universal_newlines
,
720 startupinfo
, creationflags
, shell
,
724 """Execute program (MS Windows version)"""
726 if not isinstance(args
, types
.StringTypes
):
727 args
= list2cmdline(args
)
729 # Process startup details
730 default_startupinfo
= STARTUPINFO()
731 if startupinfo
is None:
732 startupinfo
= default_startupinfo
733 if not None in (p2cread
, c2pwrite
, errwrite
):
734 startupinfo
.dwFlags |
= STARTF_USESTDHANDLES
735 startupinfo
.hStdInput
= p2cread
736 startupinfo
.hStdOutput
= c2pwrite
737 startupinfo
.hStdError
= errwrite
740 default_startupinfo
.dwFlags |
= STARTF_USESHOWWINDOW
741 default_startupinfo
.wShowWindow
= SW_HIDE
742 comspec
= os
.environ
.get("COMSPEC", "cmd.exe")
743 args
= comspec
+ " /c " + args
744 if (GetVersion() >= 0x80000000L
or
745 os
.path
.basename(comspec
).lower() == "command.com"):
746 # Win9x, or using command.com on NT. We need to
747 # use the w9xpopen intermediate program. For more
748 # information, see KB Q150956
749 # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
750 w9xpopen
= self
._find
_w
9xpopen
()
751 args
= '"%s" %s' % (w9xpopen
, args
)
752 # Not passing CREATE_NEW_CONSOLE has been known to
753 # cause random failures on win9x. Specifically a
754 # dialog: "Your program accessed mem currently in
755 # use at xxx" and a hopeful warning about the
756 # stability of your system. Cost is Ctrl+C wont
758 creationflags |
= CREATE_NEW_CONSOLE
762 hp
, ht
, pid
, tid
= CreateProcess(executable
, args
,
763 # no special security
765 # must inherit handles to pass std
772 except pywintypes
.error
, e
:
773 # Translate pywintypes.error to WindowsError, which is
774 # a subclass of OSError. FIXME: We should really
775 # translate errno using _sys_errlist (or simliar), but
776 # how can this be done from Python?
777 raise WindowsError(*e
.args
)
779 # Retain the process handle, but close the thread handle
784 # Child is launched. Close the parent's copy of those pipe
785 # handles that only the child should have open. You need
786 # to make sure that no handles to the write end of the
787 # output pipe are maintained in this process or else the
788 # pipe will not close when the child process exits and the
789 # ReadFile will hang.
790 if p2cread
is not None:
792 if c2pwrite
is not None:
794 if errwrite
is not None:
799 """Check if child process has terminated. Returns returncode
801 if self
.returncode
is None:
802 if WaitForSingleObject(self
._handle
, 0) == WAIT_OBJECT_0
:
803 self
.returncode
= GetExitCodeProcess(self
._handle
)
805 return self
.returncode
809 """Wait for child process to terminate. Returns returncode
811 if self
.returncode
is None:
812 obj
= WaitForSingleObject(self
._handle
, INFINITE
)
813 self
.returncode
= GetExitCodeProcess(self
._handle
)
815 return self
.returncode
818 def _readerthread(self
, fh
, buffer):
819 buffer.append(fh
.read())
822 def _communicate(self
, input):
823 stdout
= None # Return
824 stderr
= None # Return
828 stdout_thread
= threading
.Thread(target
=self
._readerthread
,
829 args
=(self
.stdout
, stdout
))
830 stdout_thread
.setDaemon(True)
831 stdout_thread
.start()
834 stderr_thread
= threading
.Thread(target
=self
._readerthread
,
835 args
=(self
.stderr
, stderr
))
836 stderr_thread
.setDaemon(True)
837 stderr_thread
.start()
840 if input is not None:
841 self
.stdin
.write(input)
849 # All data exchanged. Translate lists into strings.
850 if stdout
is not None:
852 if stderr
is not None:
855 # Translate newlines, if requested. We cannot let the file
856 # object do the translation: It is based on stdio, which is
857 # impossible to combine with select (unless forcing no
859 if self
.universal_newlines
and hasattr(open, 'newlines'):
861 stdout
= self
._translate
_newlines
(stdout
)
863 stderr
= self
._translate
_newlines
(stderr
)
866 return (stdout
, stderr
)
872 def _get_handles(self
, stdin
, stdout
, stderr
):
873 """Construct and return tupel with IO objects:
874 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
876 p2cread
, p2cwrite
= None, None
877 c2pread
, c2pwrite
= None, None
878 errread
, errwrite
= None, None
883 p2cread
, p2cwrite
= os
.pipe()
884 elif isinstance(stdin
, int):
887 # Assuming file-like object
888 p2cread
= stdin
.fileno()
893 c2pread
, c2pwrite
= os
.pipe()
894 elif isinstance(stdout
, int):
897 # Assuming file-like object
898 c2pwrite
= stdout
.fileno()
903 errread
, errwrite
= os
.pipe()
904 elif stderr
== STDOUT
:
906 elif isinstance(stderr
, int):
909 # Assuming file-like object
910 errwrite
= stderr
.fileno()
912 return (p2cread
, p2cwrite
,
917 def _set_cloexec_flag(self
, fd
):
919 cloexec_flag
= fcntl
.FD_CLOEXEC
920 except AttributeError:
923 old
= fcntl
.fcntl(fd
, fcntl
.F_GETFD
)
924 fcntl
.fcntl(fd
, fcntl
.F_SETFD
, old | cloexec_flag
)
927 def _close_fds(self
, but
):
928 for i
in range(3, MAXFD
):
937 def _execute_child(self
, args
, executable
, preexec_fn
, close_fds
,
938 cwd
, env
, universal_newlines
,
939 startupinfo
, creationflags
, shell
,
943 """Execute program (POSIX version)"""
945 if isinstance(args
, types
.StringTypes
):
949 args
= ["/bin/sh", "-c"] + args
951 if executable
is None:
954 # For transferring possible exec failure from child to parent
955 # The first char specifies the exception type: 0 means
956 # OSError, 1 means some other error.
957 errpipe_read
, errpipe_write
= os
.pipe()
958 self
._set
_cloexec
_flag
(errpipe_write
)
964 # Close parent's pipe ends
971 os
.close(errpipe_read
)
981 # Close pipe fds. Make sure we doesn't close the same
985 if c2pwrite
and c2pwrite
not in (p2cread
,):
987 if errwrite
and errwrite
not in (p2cread
, c2pwrite
):
990 # Close all other fds, if asked for
992 self
._close
_fds
(but
=errpipe_write
)
1001 os
.execvp(executable
, args
)
1003 os
.execvpe(executable
, args
, env
)
1006 exc_type
, exc_value
, tb
= sys
.exc_info()
1007 # Save the traceback and attach it to the exception object
1008 exc_lines
= traceback
.format_exception(exc_type
,
1011 exc_value
.child_traceback
= ''.join(exc_lines
)
1012 os
.write(errpipe_write
, pickle
.dumps(exc_value
))
1014 # This exitcode won't be reported to applications, so it
1015 # really doesn't matter what we return.
1019 os
.close(errpipe_write
)
1020 if p2cread
and p2cwrite
:
1022 if c2pwrite
and c2pread
:
1024 if errwrite
and errread
:
1027 # Wait for exec to fail or succeed; possibly raising exception
1028 data
= os
.read(errpipe_read
, 1048576) # Exceptions limited to 1 MB
1029 os
.close(errpipe_read
)
1031 os
.waitpid(self
.pid
, 0)
1032 child_exception
= pickle
.loads(data
)
1033 raise child_exception
1036 def _handle_exitstatus(self
, sts
):
1037 if os
.WIFSIGNALED(sts
):
1038 self
.returncode
= -os
.WTERMSIG(sts
)
1039 elif os
.WIFEXITED(sts
):
1040 self
.returncode
= os
.WEXITSTATUS(sts
)
1042 # Should never happen
1043 raise RuntimeError("Unknown child exit status!")
1045 _active
.remove(self
)
1049 """Check if child process has terminated. Returns returncode
1051 if self
.returncode
is None:
1053 pid
, sts
= os
.waitpid(self
.pid
, os
.WNOHANG
)
1055 self
._handle
_exitstatus
(sts
)
1058 return self
.returncode
1062 """Wait for child process to terminate. Returns returncode
1064 if self
.returncode
is None:
1065 pid
, sts
= os
.waitpid(self
.pid
, 0)
1066 self
._handle
_exitstatus
(sts
)
1067 return self
.returncode
1070 def _communicate(self
, input):
1073 stdout
= None # Return
1074 stderr
= None # Return
1077 # Flush stdio buffer. This might block, if the user has
1078 # been writing to .stdin in an uncontrolled fashion.
1081 write_set
.append(self
.stdin
)
1085 read_set
.append(self
.stdout
)
1088 read_set
.append(self
.stderr
)
1091 while read_set
or write_set
:
1092 rlist
, wlist
, xlist
= select
.select(read_set
, write_set
, [])
1094 if self
.stdin
in wlist
:
1095 # When select has indicated that the file is writable,
1096 # we can write up to PIPE_BUF bytes without risk
1097 # blocking. POSIX defines PIPE_BUF >= 512
1098 bytes_written
= os
.write(self
.stdin
.fileno(), input[:512])
1099 input = input[bytes_written
:]
1102 write_set
.remove(self
.stdin
)
1104 if self
.stdout
in rlist
:
1105 data
= os
.read(self
.stdout
.fileno(), 1024)
1108 read_set
.remove(self
.stdout
)
1111 if self
.stderr
in rlist
:
1112 data
= os
.read(self
.stderr
.fileno(), 1024)
1115 read_set
.remove(self
.stderr
)
1118 # All data exchanged. Translate lists into strings.
1119 if stdout
is not None:
1120 stdout
= ''.join(stdout
)
1121 if stderr
is not None:
1122 stderr
= ''.join(stderr
)
1124 # Translate newlines, if requested. We cannot let the file
1125 # object do the translation: It is based on stdio, which is
1126 # impossible to combine with select (unless forcing no
1128 if self
.universal_newlines
and hasattr(open, 'newlines'):
1130 stdout
= self
._translate
_newlines
(stdout
)
1132 stderr
= self
._translate
_newlines
(stderr
)
1135 return (stdout
, stderr
)
1140 # Example 1: Simple redirection: Get process list
1142 plist
= Popen(["ps"], stdout
=PIPE
).communicate()[0]
1143 print "Process list:"
1147 # Example 2: Change uid before executing child
1149 if os
.getuid() == 0:
1150 p
= Popen(["id"], preexec_fn
=lambda: os
.setuid(100))
1154 # Example 3: Connecting several subprocesses
1156 print "Looking for 'hda'..."
1157 p1
= Popen(["dmesg"], stdout
=PIPE
)
1158 p2
= Popen(["grep", "hda"], stdin
=p1
.stdout
, stdout
=PIPE
)
1159 print repr(p2
.communicate()[0])
1162 # Example 4: Catch execution error
1165 print "Trying a weird file..."
1167 print Popen(["/this/path/does/not/exist"]).communicate()
1169 if e
.errno
== errno
.ENOENT
:
1170 print "The file didn't exist. I thought so..."
1171 print "Child traceback:"
1172 print e
.child_traceback
1174 print "Error", e
.errno
1176 print >>sys
.stderr
, "Gosh. No error."
1179 def _demo_windows():
1181 # Example 1: Connecting several subprocesses
1183 print "Looking for 'PROMPT' in set output..."
1184 p1
= Popen("set", stdout
=PIPE
, shell
=True)
1185 p2
= Popen('find "PROMPT"', stdin
=p1
.stdout
, stdout
=PIPE
)
1186 print repr(p2
.communicate()[0])
1189 # Example 2: Simple execution of program
1191 print "Executing calc..."
1196 if __name__
== "__main__":