cpython/Doc/library/subprocess.rst

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:mod:`subprocess` --- Subprocess management
===========================================
.. module:: subprocess
:synopsis: Subprocess management.
.. moduleauthor:: Peter Åstrand <astrand@lysator.liu.se>
.. sectionauthor:: Peter Åstrand <astrand@lysator.liu.se>
The :mod:`subprocess` module allows you to spawn new processes, connect to their
input/output/error pipes, and obtain their return codes. This module intends to
replace several other, older modules and functions, such as::
os.system
os.spawn*
Information about how the :mod:`subprocess` module can be used to replace these
modules and functions can be found in the following sections.
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.. seealso::
:pep:`324` -- PEP proposing the subprocess module
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Using the subprocess Module
---------------------------
The recommended approach to invoking subprocesses is to use the following
convenience functions for all use cases they can handle. For more advanced
use cases, the underlying :class:`Popen` interface can be used directly.
.. function:: call(args, *, stdin=None, stdout=None, stderr=None, shell=False)
Run the command described by *args*. Wait for command to complete, then
return the :attr:`returncode` attribute.
The arguments shown above are merely the most common ones, described below
in :ref:`frequently-used-arguments` (hence the slightly odd notation in
the abbreviated signature). The full function signature is the same as
that of the :class:`Popen` constructor - this functions passes all
supplied arguments directly through to that interface.
Examples::
>>> subprocess.call(["ls", "-l"])
0
>>> subprocess.call("exit 1", shell=True)
1
.. warning::
Invoking the system shell with ``shell=True`` can be a security hazard
if combined with untrusted input. See the warning under
:ref:`frequently-used-arguments` for details.
.. note::
Do not use ``stdout=PIPE`` or ``stderr=PIPE`` with this function. As
the pipes are not being read in the current process, the child
process may block if it generates enough output to a pipe to fill up
the OS pipe buffer.
.. function:: check_call(args, *, stdin=None, stdout=None, stderr=None, shell=False)
Run command with arguments. Wait for command to complete. If the return
code was zero then return, otherwise raise :exc:`CalledProcessError`. The
:exc:`CalledProcessError` object will have the return code in the
:attr:`returncode` attribute.
The arguments shown above are merely the most common ones, described below
in :ref:`frequently-used-arguments` (hence the slightly odd notation in
the abbreviated signature). The full function signature is the same as
that of the :class:`Popen` constructor - this functions passes all
supplied arguments directly through to that interface.
Examples::
>>> subprocess.check_call(["ls", "-l"])
0
>>> subprocess.check_call("exit 1", shell=True)
Traceback (most recent call last):
...
subprocess.CalledProcessError: Command 'exit 1' returned non-zero exit status 1
.. versionadded:: 2.5
.. warning::
Invoking the system shell with ``shell=True`` can be a security hazard
if combined with untrusted input. See the warning under
:ref:`frequently-used-arguments` for details.
.. note::
Do not use ``stdout=PIPE`` or ``stderr=PIPE`` with this function. As
the pipes are not being read in the current process, the child
process may block if it generates enough output to a pipe to fill up
the OS pipe buffer.
.. function:: check_output(args, *, stdin=None, stderr=None, shell=False, universal_newlines=False)
Run command with arguments and return its output as a byte string.
If the return code was non-zero it raises a :exc:`CalledProcessError`. The
:exc:`CalledProcessError` object will have the return code in the
:attr:`returncode` attribute and any output in the :attr:`output`
attribute.
The arguments shown above are merely the most common ones, described below
in :ref:`frequently-used-arguments` (hence the slightly odd notation in
the abbreviated signature). The full function signature is largely the
same as that of the :class:`Popen` constructor, except that *stdout* is
not permitted as it is used internally. All other supplied arguments are
passed directly through to the :class:`Popen` constructor.
Examples::
>>> subprocess.check_output(["echo", "Hello World!"])
b'Hello World!\n'
>>> subprocess.check_output(["echo", "Hello World!"], universal_newlines=True)
'Hello World!\n'
>>> subprocess.check_output("exit 1", shell=True)
Traceback (most recent call last):
...
subprocess.CalledProcessError: Command 'exit 1' returned non-zero exit status 1
By default, this function will return the data as encoded bytes. The actual
encoding of the output data may depend on the command being invoked, so the
decoding to text will often need to be handled at the application level.
This behaviour may be overridden by setting *universal_newlines* to
:const:`True` as described below in :ref:`frequently-used-arguments`.
To also capture standard error in the result, use
``stderr=subprocess.STDOUT``::
>>> subprocess.check_output(
... "ls non_existent_file; exit 0",
... stderr=subprocess.STDOUT,
... shell=True)
'ls: non_existent_file: No such file or directory\n'
.. versionadded:: 2.7
.. warning::
Invoking the system shell with ``shell=True`` can be a security hazard
if combined with untrusted input. See the warning under
:ref:`frequently-used-arguments` for details.
.. note::
Do not use ``stderr=PIPE`` with this function. As the pipe is not being
read in the current process, the child process may block if it
generates enough output to the pipe to fill up the OS pipe buffer.
.. data:: PIPE
Special value that can be used as the *stdin*, *stdout* or *stderr* argument
to :class:`Popen` and indicates that a pipe to the standard stream should be
opened.
.. data:: STDOUT
Special value that can be used as the *stderr* argument to :class:`Popen` and
indicates that standard error should go into the same handle as standard
output.
.. _frequently-used-arguments:
Frequently Used Arguments
^^^^^^^^^^^^^^^^^^^^^^^^^
To support a wide variety of use cases, the :class:`Popen` constructor (and
the convenience functions) accept a large number of optional arguments. For
most typical use cases, many of these arguments can be safely left at their
default values. The arguments that are most commonly needed are:
*args* is required for all calls and should be a string, or a sequence of
program arguments. Providing a sequence of arguments is generally
preferred, as it allows the module to take care of any required escaping
and quoting of arguments (e.g. to permit spaces in file names). If passing
a single string, either *shell* must be :const:`True` (see below) or else
the string must simply name the program to be executed without specifying
any arguments.
*stdin*, *stdout* and *stderr* specify the executed program's standard input,
standard output and standard error file handles, respectively. Valid values
are :data:`PIPE`, an existing file descriptor (a positive integer), an
existing file object, and ``None``. :data:`PIPE` indicates that a new pipe
to the child should be created. With the default settings of ``None``, no
redirection will occur; the child's file handles will be inherited from the
parent. Additionally, *stderr* can be :data:`STDOUT`, which indicates that
the stderr data from the child process should be captured into the same file
handle as for stdout.
When *stdout* or *stderr* are pipes and *universal_newlines* is
:const:`True` then the output data is assumed to be encoded as UTF-8 and
will automatically be decoded to text. All line endings will be converted
to ``'\n'`` as described for the universal newlines `'U'`` mode argument
to :func:`open`.
If *shell* is :const:`True`, the specified command will be executed through
the shell. This can be useful if you are using Python primarily for the
enhanced control flow it offers over most system shells and still want
access to other shell features such as filename wildcards, shell pipes and
environment variable expansion.
.. warning::
Executing shell commands that incorporate unsanitized input from an
untrusted source makes a program vulnerable to `shell injection
<http://en.wikipedia.org/wiki/Shell_injection#Shell_injection>`_,
a serious security flaw which can result in arbitrary command execution.
For this reason, the use of *shell=True* is **strongly discouraged** in cases
where the command string is constructed from external input::
>>> from subprocess import call
>>> filename = input("What file would you like to display?\n")
What file would you like to display?
non_existent; rm -rf / #
>>> call("cat " + filename, shell=True) # Uh-oh. This will end badly...
``shell=False`` disables all shell based features, but does not suffer
from this vulnerability; see the Note in the :class:`Popen` constructor
documentation for helpful hints in getting ``shell=False`` to work.
These options, along with all of the other options, are described in more
detail in the :class:`Popen` constructor documentation.
Popen Constuctor
^^^^^^^^^^^^^^^^
The underlying process creation and management in this module is handled by
the :class:`Popen` class. It offers a lot of flexibility so that developers
are able to handle the less common cases not covered by the convenience
functions.
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.. class:: Popen(args, bufsize=0, executable=None, stdin=None, stdout=None, stderr=None, preexec_fn=None, close_fds=True, shell=False, cwd=None, env=None, universal_newlines=False, startupinfo=None, creationflags=0, restore_signals=True, start_new_session=False, pass_fds=())
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Arguments are:
*args* should be a string, or a sequence of program arguments. The program
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to execute is normally the first item in the args sequence or the string if
a string is given, but can be explicitly set by using the *executable*
argument. When *executable* is given, the first item in the args sequence
is still treated by most programs as the command name, which can then be
different from the actual executable name. On Unix, it becomes the display
name for the executing program in utilities such as :program:`ps`.
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On Unix, with *shell=False* (default): In this case, the Popen class uses
:meth:`os.execvp` like behavior to execute the child program.
*args* should normally be a
sequence. If a string is specified for *args*, it will be used as the name
or path of the program to execute; this will only work if the program is
being given no arguments.
.. note::
:meth:`shlex.split` can be useful when determining the correct
tokenization for *args*, especially in complex cases::
>>> import shlex, subprocess
>>> command_line = input()
/bin/vikings -input eggs.txt -output "spam spam.txt" -cmd "echo '$MONEY'"
>>> args = shlex.split(command_line)
>>> print(args)
['/bin/vikings', '-input', 'eggs.txt', '-output', 'spam spam.txt', '-cmd', "echo '$MONEY'"]
>>> p = subprocess.Popen(args) # Success!
Note in particular that options (such as *-input*) and arguments (such
as *eggs.txt*) that are separated by whitespace in the shell go in separate
list elements, while arguments that need quoting or backslash escaping when
used in the shell (such as filenames containing spaces or the *echo* command
shown above) are single list elements.
On Unix, with *shell=True*: If args is a string, it specifies the command
string to execute through the shell. This means that the string must be
formatted exactly as it would be when typed at the shell prompt. This
includes, for example, quoting or backslash escaping filenames with spaces in
them. If *args* is a sequence, the first item specifies the command string, and
any additional items will be treated as additional arguments to the shell
itself. That is to say, *Popen* does the equivalent of::
Popen(['/bin/sh', '-c', args[0], args[1], ...])
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.. warning::
Enabling this option can be a security hazard if combined with untrusted
input. See the warning under :ref:`frequently-used-arguments`
for details.
On Windows: the :class:`Popen` class uses CreateProcess() to execute the
child program, which operates on strings. If *args* is a sequence, it will
be converted to a string in a manner described in
:ref:`converting-argument-sequence`.
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*bufsize*, if given, has the same meaning as the corresponding argument to the
built-in open() function: :const:`0` means unbuffered, :const:`1` means line
buffered, any other positive value means use a buffer of (approximately) that
size. A negative *bufsize* means to use the system default, which usually means
fully buffered. The default value for *bufsize* is :const:`0` (unbuffered).
.. note::
If you experience performance issues, it is recommended that you try to
enable buffering by setting *bufsize* to either -1 or a large enough
positive value (such as 4096).
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The *executable* argument specifies the program to execute. It is very seldom
needed: Usually, the program to execute is defined by the *args* argument. If
``shell=True``, the *executable* argument specifies which shell to use. On Unix,
the default shell is :file:`/bin/sh`. On Windows, the default shell is
specified by the :envvar:`COMSPEC` environment variable. The only reason you
would need to specify ``shell=True`` on Windows is where the command you
wish to execute is actually built in to the shell, eg ``dir``, ``copy``.
You don't need ``shell=True`` to run a batch file, nor to run a console-based
executable.
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*stdin*, *stdout* and *stderr* specify the executed program's standard input,
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standard output and standard error file handles, respectively. Valid values
are :data:`PIPE`, an existing file descriptor (a positive integer), an
existing :term:`file object`, and ``None``. :data:`PIPE` indicates that a
new pipe to the child should be created. With the default settings of
``None``, no redirection will occur; the child's file handles will be
inherited from the parent. Additionally, *stderr* can be :data:`STDOUT`,
which indicates that the stderr data from the applications should be
captured into the same file handle as for stdout.
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If *preexec_fn* is set to a callable object, this object will be called in the
child process just before the child is executed.
(Unix only)
.. warning::
The *preexec_fn* parameter is not safe to use in the presence of threads
in your application. The child process could deadlock before exec is
called.
If you must use it, keep it trivial! Minimize the number of libraries
you call into.
.. note::
If you need to modify the environment for the child use the *env*
parameter rather than doing it in a *preexec_fn*.
The *start_new_session* parameter can take the place of a previously
common use of *preexec_fn* to call os.setsid() in the child.
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If *close_fds* is true, all file descriptors except :const:`0`, :const:`1` and
:const:`2` will be closed before the child process is executed. (Unix only).
The default varies by platform: Always true on Unix. On Windows it is
true when *stdin*/*stdout*/*stderr* are :const:`None`, false otherwise.
On Windows, if *close_fds* is true then no handles will be inherited by the
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child process. Note that on Windows, you cannot set *close_fds* to true and
also redirect the standard handles by setting *stdin*, *stdout* or *stderr*.
.. versionchanged:: 3.2
The default for *close_fds* was changed from :const:`False` to
what is described above.
*pass_fds* is an optional sequence of file descriptors to keep open
between the parent and child. Providing any *pass_fds* forces
*close_fds* to be :const:`True`. (Unix only)
.. versionadded:: 3.2
The *pass_fds* parameter was added.
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If *cwd* is not ``None``, the child's current directory will be changed to *cwd*
before it is executed. Note that this directory is not considered when
searching the executable, so you can't specify the program's path relative to
*cwd*.
If *restore_signals* is True (the default) all signals that Python has set to
SIG_IGN are restored to SIG_DFL in the child process before the exec.
Currently this includes the SIGPIPE, SIGXFZ and SIGXFSZ signals.
(Unix only)
.. versionchanged:: 3.2
*restore_signals* was added.
If *start_new_session* is True the setsid() system call will be made in the
child process prior to the execution of the subprocess. (Unix only)
.. versionchanged:: 3.2
*start_new_session* was added.
Merged revisions 62386-62387,62389-62393,62396,62400-62402,62407,62409-62410,62412-62414,62418-62419 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r62386 | christian.heimes | 2008-04-19 04:23:57 +0200 (Sat, 19 Apr 2008) | 2 lines Added kill, terminate and send_signal to subprocess.Popen The bits and pieces for the Windows side were already in place. The POSIX side is trivial (as usual) and uses os.kill(). ........ r62387 | georg.brandl | 2008-04-19 10:23:59 +0200 (Sat, 19 Apr 2008) | 2 lines Fix-up docs for revision 62386. ........ r62389 | georg.brandl | 2008-04-19 18:57:43 +0200 (Sat, 19 Apr 2008) | 2 lines #2369: clarify that copyfile() doesn't take a target directory. ........ r62390 | georg.brandl | 2008-04-19 18:58:28 +0200 (Sat, 19 Apr 2008) | 2 lines #2634: clarify meaning of env parameter to spawn/exec*e. ........ r62391 | georg.brandl | 2008-04-19 18:58:49 +0200 (Sat, 19 Apr 2008) | 2 lines #2633: clarify meaning of env parameter. ........ r62392 | georg.brandl | 2008-04-19 18:59:16 +0200 (Sat, 19 Apr 2008) | 2 lines #2631: clarify IMPORT_NAME semantics. ........ r62393 | georg.brandl | 2008-04-19 19:00:14 +0200 (Sat, 19 Apr 2008) | 2 lines :func: et al. should *not* include the parens. ........ r62396 | mark.dickinson | 2008-04-19 20:51:48 +0200 (Sat, 19 Apr 2008) | 5 lines Additional tests for math.pow, and extra special-case handling code in math.pow, in the hope of making all tests pass on the alpha Tru64 buildbot. ........ r62400 | mark.dickinson | 2008-04-19 21:41:52 +0200 (Sat, 19 Apr 2008) | 3 lines Additional special-case handling for math.pow. Windows/VS2008 doesn't like (-1)**(+-inf). ........ r62401 | benjamin.peterson | 2008-04-19 21:47:34 +0200 (Sat, 19 Apr 2008) | 2 lines Complete documentation for errors argument of io's open and TextIOWrapper ........ r62402 | mark.dickinson | 2008-04-19 22:31:16 +0200 (Sat, 19 Apr 2008) | 2 lines Document updates to math and cmath modules. ........ r62407 | georg.brandl | 2008-04-19 23:28:38 +0200 (Sat, 19 Apr 2008) | 2 lines Update template for newest Sphinx. ........ r62409 | mark.dickinson | 2008-04-19 23:35:35 +0200 (Sat, 19 Apr 2008) | 5 lines Correct documentation for math.pow; 0**nan is nan, not 0. (But nan**0 and 1**nan are 1.) Also fix minor typo: 'quite NaN' -> 'quiet NaN' ........ r62410 | mark.dickinson | 2008-04-19 23:49:22 +0200 (Sat, 19 Apr 2008) | 4 lines Move asinh documentation to the proper place. Remove meaningless 'in radians' from inverse hyperbolic functions. ........ r62412 | mark.dickinson | 2008-04-20 03:22:30 +0200 (Sun, 20 Apr 2008) | 5 lines Report additional diagnostic information in test_math, to help track down debian-alpha buildbot failure. ........ r62413 | mark.dickinson | 2008-04-20 03:39:24 +0200 (Sun, 20 Apr 2008) | 3 lines FreeBSD doesn't follow C99 for modf(inf); so add explicit special-value handling to math.modf code. ........ r62414 | mark.dickinson | 2008-04-20 06:13:13 +0200 (Sun, 20 Apr 2008) | 5 lines Yet more explicit special case handling to make math.pow behave on alpha Tru64. All IEEE 754 special values are now handled directly; only the finite**finite case is handled by libm. ........ r62418 | mark.dickinson | 2008-04-20 18:13:17 +0200 (Sun, 20 Apr 2008) | 7 lines Issue 2662: Initialize special value tables dynamically (i.e. when cmath module is loaded) instead of statically. This fixes compile-time problems on platforms where HUGE_VAL is an extern variable rather than a constant. Thanks Hirokazu Yamamoto for the patch. ........ r62419 | andrew.kuchling | 2008-04-20 18:54:02 +0200 (Sun, 20 Apr 2008) | 1 line Move description of math module changes; various edits to description of cmath changes ........
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If *env* is not ``None``, it must be a mapping that defines the environment
variables for the new process; these are used instead of the default
behavior of inheriting the current process' environment.
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.. note::
If specified, *env* must provide any variables required for the program to
execute. On Windows, in order to run a `side-by-side assembly`_ the
specified *env* **must** include a valid :envvar:`SystemRoot`.
.. _side-by-side assembly: http://en.wikipedia.org/wiki/Side-by-Side_Assembly
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If *universal_newlines* is :const:`True`, the file objects stdout and stderr are
opened as text files, but lines may be terminated by any of ``'\n'``, the Unix
end-of-line convention, ``'\r'``, the old Macintosh convention or ``'\r\n'``, the
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Windows convention. All of these external representations are seen as ``'\n'``
by the Python program.
.. note::
This feature is only available if Python is built with universal newline
support (the default). Also, the newlines attribute of the file objects
:attr:`stdout`, :attr:`stdin` and :attr:`stderr` are not updated by the
:meth:`communicate` method.
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If given, *startupinfo* will be a :class:`STARTUPINFO` object, which is
passed to the underlying ``CreateProcess`` function.
*creationflags*, if given, can be :data:`CREATE_NEW_CONSOLE` or
:data:`CREATE_NEW_PROCESS_GROUP`. (Windows only)
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Popen objects are supported as context managers via the :keyword:`with` statement:
on exit, standard file descriptors are closed, and the process is waited for.
::
with Popen(["ifconfig"], stdout=PIPE) as proc:
log.write(proc.stdout.read())
.. versionchanged:: 3.2
Added context manager support.
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Exceptions
^^^^^^^^^^
Exceptions raised in the child process, before the new program has started to
execute, will be re-raised in the parent. Additionally, the exception object
will have one extra attribute called :attr:`child_traceback`, which is a string
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containing traceback information from the child's point of view.
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The most common exception raised is :exc:`OSError`. This occurs, for example,
when trying to execute a non-existent file. Applications should prepare for
:exc:`OSError` exceptions.
A :exc:`ValueError` will be raised if :class:`Popen` is called with invalid
arguments.
:func:`check_call` and :func:`check_output` will raise
:exc:`CalledProcessError` if the called process returns a non-zero return
code.
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Security
^^^^^^^^
Unlike some other popen functions, this implementation will never call a
system shell implicitly. This means that all characters, including shell
metacharacters, can safely be passed to child processes. Obviously, if the
shell is invoked explicitly, then it is the application's responsibility to
ensure that all whitespace and metacharacters are quoted appropriately.
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Popen Objects
-------------
Instances of the :class:`Popen` class have the following methods:
.. method:: Popen.poll()
Check if child process has terminated. Set and return :attr:`returncode`
attribute.
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.. method:: Popen.wait()
Wait for child process to terminate. Set and return :attr:`returncode`
attribute.
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Merged revisions 65437,65469,65476,65480,65502,65528,65539,65543,65558,65561-65562,65565,65591,65601,65608,65610,65639 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r65437 | georg.brandl | 2008-08-03 22:28:55 +0000 (Sun, 03 Aug 2008) | 2 lines Note the removal of several committers. ........ r65469 | gregory.p.smith | 2008-08-04 01:03:50 +0000 (Mon, 04 Aug 2008) | 3 lines issue1606: Add warnings to the subprocess documentation about common pitfalls of using pipes that cause deadlocks. ........ r65476 | georg.brandl | 2008-08-04 06:29:36 +0000 (Mon, 04 Aug 2008) | 2 lines Fix markup. ........ r65480 | georg.brandl | 2008-08-04 07:31:50 +0000 (Mon, 04 Aug 2008) | 3 lines Clarify the meaning of the select() parameters and sync names with docstring. ........ r65502 | gregory.p.smith | 2008-08-04 18:34:07 +0000 (Mon, 04 Aug 2008) | 2 lines more cleanup ups of the recently added warnings in the subprocess docs. ........ r65528 | brett.cannon | 2008-08-04 21:52:25 +0000 (Mon, 04 Aug 2008) | 4 lines Add a note about all the modules/packages changed to silence -3 warnings. More changes are needed once some decisions are made, but this is the work up to this point. ........ r65539 | andrew.kuchling | 2008-08-05 01:38:08 +0000 (Tue, 05 Aug 2008) | 6 lines #3367 from Kristjan Valur Jonsson: If a PyTokenizer_FromString() is called with an empty string, the tokenizer's line_start member never gets initialized. Later, it is compared with the token pointer 'a' in parsetok.c:193 and that behavior can result in undefined behavior. ........ r65543 | andrew.kuchling | 2008-08-05 02:05:23 +0000 (Tue, 05 Aug 2008) | 1 line #3367: revert rev. 65539: this change causes test_parser to fail ........ r65558 | georg.brandl | 2008-08-06 17:20:41 +0000 (Wed, 06 Aug 2008) | 2 lines Fix longstringitem definition. #3505. ........ r65561 | mark.dickinson | 2008-08-06 20:12:30 +0000 (Wed, 06 Aug 2008) | 2 lines Docstring typo ........ r65562 | mark.dickinson | 2008-08-06 21:36:57 +0000 (Wed, 06 Aug 2008) | 2 lines Remove duplicate import ........ r65565 | andrew.kuchling | 2008-08-07 01:47:34 +0000 (Thu, 07 Aug 2008) | 1 line Add some items ........ r65591 | georg.brandl | 2008-08-08 06:42:20 +0000 (Fri, 08 Aug 2008) | 2 lines #3519: callee is an expression too. ........ r65601 | georg.brandl | 2008-08-08 15:34:34 +0000 (Fri, 08 Aug 2008) | 2 lines Remove mention of backquotes in the tutorial. ........ r65608 | guido.van.rossum | 2008-08-09 14:55:34 +0000 (Sat, 09 Aug 2008) | 2 lines Add news item about _sre.compile() re-bytecode validator. ........ r65610 | antoine.pitrou | 2008-08-09 17:27:23 +0000 (Sat, 09 Aug 2008) | 3 lines move NEWS entry to the appropriate section (oops!) ........ r65639 | georg.brandl | 2008-08-11 10:27:31 +0000 (Mon, 11 Aug 2008) | 2 lines #3540: fix exception name. ........
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.. warning::
This will deadlock when using ``stdout=PIPE`` and/or
``stderr=PIPE`` and the child process generates enough output to
a pipe such that it blocks waiting for the OS pipe buffer to
accept more data. Use :meth:`communicate` to avoid that.
Merged revisions 65437,65469,65476,65480,65502,65528,65539,65543,65558,65561-65562,65565,65591,65601,65608,65610,65639 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r65437 | georg.brandl | 2008-08-03 22:28:55 +0000 (Sun, 03 Aug 2008) | 2 lines Note the removal of several committers. ........ r65469 | gregory.p.smith | 2008-08-04 01:03:50 +0000 (Mon, 04 Aug 2008) | 3 lines issue1606: Add warnings to the subprocess documentation about common pitfalls of using pipes that cause deadlocks. ........ r65476 | georg.brandl | 2008-08-04 06:29:36 +0000 (Mon, 04 Aug 2008) | 2 lines Fix markup. ........ r65480 | georg.brandl | 2008-08-04 07:31:50 +0000 (Mon, 04 Aug 2008) | 3 lines Clarify the meaning of the select() parameters and sync names with docstring. ........ r65502 | gregory.p.smith | 2008-08-04 18:34:07 +0000 (Mon, 04 Aug 2008) | 2 lines more cleanup ups of the recently added warnings in the subprocess docs. ........ r65528 | brett.cannon | 2008-08-04 21:52:25 +0000 (Mon, 04 Aug 2008) | 4 lines Add a note about all the modules/packages changed to silence -3 warnings. More changes are needed once some decisions are made, but this is the work up to this point. ........ r65539 | andrew.kuchling | 2008-08-05 01:38:08 +0000 (Tue, 05 Aug 2008) | 6 lines #3367 from Kristjan Valur Jonsson: If a PyTokenizer_FromString() is called with an empty string, the tokenizer's line_start member never gets initialized. Later, it is compared with the token pointer 'a' in parsetok.c:193 and that behavior can result in undefined behavior. ........ r65543 | andrew.kuchling | 2008-08-05 02:05:23 +0000 (Tue, 05 Aug 2008) | 1 line #3367: revert rev. 65539: this change causes test_parser to fail ........ r65558 | georg.brandl | 2008-08-06 17:20:41 +0000 (Wed, 06 Aug 2008) | 2 lines Fix longstringitem definition. #3505. ........ r65561 | mark.dickinson | 2008-08-06 20:12:30 +0000 (Wed, 06 Aug 2008) | 2 lines Docstring typo ........ r65562 | mark.dickinson | 2008-08-06 21:36:57 +0000 (Wed, 06 Aug 2008) | 2 lines Remove duplicate import ........ r65565 | andrew.kuchling | 2008-08-07 01:47:34 +0000 (Thu, 07 Aug 2008) | 1 line Add some items ........ r65591 | georg.brandl | 2008-08-08 06:42:20 +0000 (Fri, 08 Aug 2008) | 2 lines #3519: callee is an expression too. ........ r65601 | georg.brandl | 2008-08-08 15:34:34 +0000 (Fri, 08 Aug 2008) | 2 lines Remove mention of backquotes in the tutorial. ........ r65608 | guido.van.rossum | 2008-08-09 14:55:34 +0000 (Sat, 09 Aug 2008) | 2 lines Add news item about _sre.compile() re-bytecode validator. ........ r65610 | antoine.pitrou | 2008-08-09 17:27:23 +0000 (Sat, 09 Aug 2008) | 3 lines move NEWS entry to the appropriate section (oops!) ........ r65639 | georg.brandl | 2008-08-11 10:27:31 +0000 (Mon, 11 Aug 2008) | 2 lines #3540: fix exception name. ........
2008-08-12 05:18:18 -03:00
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.. method:: Popen.communicate(input=None)
Interact with process: Send data to stdin. Read data from stdout and stderr,
until end-of-file is reached. Wait for process to terminate. The optional
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*input* argument should be a byte string to be sent to the child process, or
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``None``, if no data should be sent to the child.
Merged revisions 67531-67532,67538,67553-67554,67556-67557,67571,67574-67575,67579-67580,67591,67597,67608,67631 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r67531 | georg.brandl | 2008-12-04 19:54:05 +0100 (Thu, 04 Dec 2008) | 2 lines Add reference to enumerate() to indices example. ........ r67532 | georg.brandl | 2008-12-04 19:59:16 +0100 (Thu, 04 Dec 2008) | 2 lines Add another heapq example. ........ r67538 | georg.brandl | 2008-12-04 22:28:16 +0100 (Thu, 04 Dec 2008) | 2 lines Clarification to avoid confusing output with file descriptors. ........ r67553 | georg.brandl | 2008-12-05 08:49:49 +0100 (Fri, 05 Dec 2008) | 2 lines #4408: document regex.groups. ........ r67554 | georg.brandl | 2008-12-05 08:52:26 +0100 (Fri, 05 Dec 2008) | 2 lines #4409: fix asterisks looking like footnotes. ........ r67556 | georg.brandl | 2008-12-05 09:02:17 +0100 (Fri, 05 Dec 2008) | 2 lines #4441: improve doc for os.open() flags. ........ r67557 | georg.brandl | 2008-12-05 09:06:57 +0100 (Fri, 05 Dec 2008) | 2 lines Add an index entry for "subclassing immutable types". ........ r67571 | georg.brandl | 2008-12-05 10:13:45 +0100 (Fri, 05 Dec 2008) | 2 lines Use markup. ........ r67574 | georg.brandl | 2008-12-05 10:25:32 +0100 (Fri, 05 Dec 2008) | 2 lines #4441 followup: Add link to open() docs for Windows. ........ r67575 | georg.brandl | 2008-12-05 12:34:51 +0100 (Fri, 05 Dec 2008) | 2 lines #4544: add `dedent` to textwrap.__all__. ........ r67579 | georg.brandl | 2008-12-05 16:29:39 +0100 (Fri, 05 Dec 2008) | 2 lines #4517: add "special method" glossary entry and clarify when __getattribute__ is bypassed. ........ r67580 | georg.brandl | 2008-12-05 16:32:29 +0100 (Fri, 05 Dec 2008) | 2 lines #4478: document that copyfile() can raise Error. ........ r67591 | georg.brandl | 2008-12-05 19:00:06 +0100 (Fri, 05 Dec 2008) | 2 lines Followup to #4511: add link from decorator glossary entry to definition. ........ r67597 | georg.brandl | 2008-12-05 20:03:19 +0100 (Fri, 05 Dec 2008) | 2 lines Remove confusing sentence part. ........ r67608 | georg.brandl | 2008-12-06 12:57:12 +0100 (Sat, 06 Dec 2008) | 2 lines Follow-up to #4488: document PIPE and STDOUT properly. ........ r67631 | georg.brandl | 2008-12-07 12:54:07 +0100 (Sun, 07 Dec 2008) | 2 lines Add link to the favicon to the docs. ........
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:meth:`communicate` returns a tuple ``(stdoutdata, stderrdata)``.
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Merged revisions 59107-59186 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk (Note: some conflicts in the PCbuild9 directory reverted. Sorry Christian!) ........ r59120 | christian.heimes | 2007-11-22 03:21:16 -0800 (Thu, 22 Nov 2007) | 3 lines Backport of the PCbuild9 directory from the py3k branch. I've finished the last task for the PCbuild9 directory today. I don't think there is much left to do. Now you can all play around with the shiny new VS 2008 and try the PGO builds. I was able to get a speed improvement of about 10% on py3k. Have fun! :) ........ r59126 | brett.cannon | 2007-11-22 16:06:51 -0800 (Thu, 22 Nov 2007) | 2 lines Fix a bug in the test for using __loader__.get_data(). ........ r59131 | christian.heimes | 2007-11-22 23:05:03 -0800 (Thu, 22 Nov 2007) | 1 line Backport of PCbuild9 fixes from py3k r59130 ........ r59132 | christian.heimes | 2007-11-23 01:10:36 -0800 (Fri, 23 Nov 2007) | 2 lines Applied patch #1754273 and #1754271 from Thomas Glee The patches are adding deprecation warnings for back ticks and <> ........ r59133 | christian.heimes | 2007-11-23 04:12:02 -0800 (Fri, 23 Nov 2007) | 2 lines Fixed problems in the last commit. Filenames and line numbers weren't reported correctly. Backquotes still don't report the correct file. The AST nodes only contain the line number but not the file name. ........ r59134 | christian.heimes | 2007-11-23 04:16:35 -0800 (Fri, 23 Nov 2007) | 1 line How did the comment get there? ........ r59135 | christian.heimes | 2007-11-23 05:25:31 -0800 (Fri, 23 Nov 2007) | 1 line And yet another fix for the patch. Paul Moore has send me a note that I've missed a declaration. The additional code has moved the declaration in the middle of the block. ........ r59136 | andrew.kuchling | 2007-11-23 05:37:39 -0800 (Fri, 23 Nov 2007) | 1 line Add item ........ r59137 | skip.montanaro | 2007-11-23 09:08:35 -0800 (Fri, 23 Nov 2007) | 2 lines Make trace and doctest play nice together (issue 1429818). Will backport. ........ r59139 | skip.montanaro | 2007-11-23 09:12:47 -0800 (Fri, 23 Nov 2007) | 1 line issue 1429818 ........ r59144 | facundo.batista | 2007-11-23 09:59:00 -0800 (Fri, 23 Nov 2007) | 10 lines Major change in the internal structure of the Decimal number: now it does not store the mantissa as a tuple of numbers, but as a string. This avoids a lot of conversions, and achieves a speedup of 40%. The API remains intact. Thanks Mark Dickinson. ........ r59146 | facundo.batista | 2007-11-23 10:14:50 -0800 (Fri, 23 Nov 2007) | 3 lines Test cases from Cowlishaw, v2.57. All are pased cleanly. ........ r59156 | christian.heimes | 2007-11-23 17:36:02 -0800 (Fri, 23 Nov 2007) | 2 lines Added filename to compiling struct based on Martin's suggestion. I'm wonder why I was trying to add the filename to the node all the time. The compiling struct is more obvious. ........ r59158 | christian.heimes | 2007-11-23 17:53:59 -0800 (Fri, 23 Nov 2007) | 2 lines Backport of fixes from py3k branch svn merge -r59131:HEAD ../../py3k/PCbuild9/ . ........ r59159 | skip.montanaro | 2007-11-23 20:29:08 -0800 (Fri, 23 Nov 2007) | 1 line revert change that breaks test_doctest (which I forgot to run - sorry) ........ r59162 | skip.montanaro | 2007-11-23 20:31:15 -0800 (Fri, 23 Nov 2007) | 1 line revert ........ r59164 | georg.brandl | 2007-11-24 03:31:46 -0800 (Sat, 24 Nov 2007) | 3 lines #1344: document that you need to open std{in,out,err} with PIPE if you want communicate() to work as described. ........ r59165 | georg.brandl | 2007-11-24 03:39:13 -0800 (Sat, 24 Nov 2007) | 2 lines #1467: fix documentation for TestResult.add{Error,Failure}. ........ r59166 | georg.brandl | 2007-11-24 03:42:14 -0800 (Sat, 24 Nov 2007) | 2 lines #1355: remove mention of PyXML from xml.dom docs. ........ r59169 | amaury.forgeotdarc | 2007-11-24 05:20:22 -0800 (Sat, 24 Nov 2007) | 2 lines Warning "<> not supported in 3.x" should be enabled only when the -3 option is set. ........ r59170 | amaury.forgeotdarc | 2007-11-24 05:44:17 -0800 (Sat, 24 Nov 2007) | 3 lines Issue #1445: Fix a SystemError when accessing the ``cell_contents`` attribute of an empty cell object. Now a ValueError is raised. ........ r59172 | georg.brandl | 2007-11-24 05:56:09 -0800 (Sat, 24 Nov 2007) | 3 lines #1735632: add O_NOATIME constant to os module. Also document a few other O_ constants that were missing from documentation. ........ r59173 | skip.montanaro | 2007-11-24 06:30:47 -0800 (Sat, 24 Nov 2007) | 1 line back in these go - thanks to Titus Brown for the fix ........ r59176 | martin.v.loewis | 2007-11-24 10:33:40 -0800 (Sat, 24 Nov 2007) | 2 lines Bug #1494: Document that appendChild removes first. ........ r59186 | guido.van.rossum | 2007-11-26 14:16:49 -0800 (Mon, 26 Nov 2007) | 2 lines A thread-less variant of brownian.py, submitted by Michele Simoniato. ........
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Note that if you want to send data to the process's stdin, you need to create
the Popen object with ``stdin=PIPE``. Similarly, to get anything other than
``None`` in the result tuple, you need to give ``stdout=PIPE`` and/or
``stderr=PIPE`` too.
.. note::
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The data read is buffered in memory, so do not use this method if the data
size is large or unlimited.
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Merged revisions 62386-62387,62389-62393,62396,62400-62402,62407,62409-62410,62412-62414,62418-62419 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r62386 | christian.heimes | 2008-04-19 04:23:57 +0200 (Sat, 19 Apr 2008) | 2 lines Added kill, terminate and send_signal to subprocess.Popen The bits and pieces for the Windows side were already in place. The POSIX side is trivial (as usual) and uses os.kill(). ........ r62387 | georg.brandl | 2008-04-19 10:23:59 +0200 (Sat, 19 Apr 2008) | 2 lines Fix-up docs for revision 62386. ........ r62389 | georg.brandl | 2008-04-19 18:57:43 +0200 (Sat, 19 Apr 2008) | 2 lines #2369: clarify that copyfile() doesn't take a target directory. ........ r62390 | georg.brandl | 2008-04-19 18:58:28 +0200 (Sat, 19 Apr 2008) | 2 lines #2634: clarify meaning of env parameter to spawn/exec*e. ........ r62391 | georg.brandl | 2008-04-19 18:58:49 +0200 (Sat, 19 Apr 2008) | 2 lines #2633: clarify meaning of env parameter. ........ r62392 | georg.brandl | 2008-04-19 18:59:16 +0200 (Sat, 19 Apr 2008) | 2 lines #2631: clarify IMPORT_NAME semantics. ........ r62393 | georg.brandl | 2008-04-19 19:00:14 +0200 (Sat, 19 Apr 2008) | 2 lines :func: et al. should *not* include the parens. ........ r62396 | mark.dickinson | 2008-04-19 20:51:48 +0200 (Sat, 19 Apr 2008) | 5 lines Additional tests for math.pow, and extra special-case handling code in math.pow, in the hope of making all tests pass on the alpha Tru64 buildbot. ........ r62400 | mark.dickinson | 2008-04-19 21:41:52 +0200 (Sat, 19 Apr 2008) | 3 lines Additional special-case handling for math.pow. Windows/VS2008 doesn't like (-1)**(+-inf). ........ r62401 | benjamin.peterson | 2008-04-19 21:47:34 +0200 (Sat, 19 Apr 2008) | 2 lines Complete documentation for errors argument of io's open and TextIOWrapper ........ r62402 | mark.dickinson | 2008-04-19 22:31:16 +0200 (Sat, 19 Apr 2008) | 2 lines Document updates to math and cmath modules. ........ r62407 | georg.brandl | 2008-04-19 23:28:38 +0200 (Sat, 19 Apr 2008) | 2 lines Update template for newest Sphinx. ........ r62409 | mark.dickinson | 2008-04-19 23:35:35 +0200 (Sat, 19 Apr 2008) | 5 lines Correct documentation for math.pow; 0**nan is nan, not 0. (But nan**0 and 1**nan are 1.) Also fix minor typo: 'quite NaN' -> 'quiet NaN' ........ r62410 | mark.dickinson | 2008-04-19 23:49:22 +0200 (Sat, 19 Apr 2008) | 4 lines Move asinh documentation to the proper place. Remove meaningless 'in radians' from inverse hyperbolic functions. ........ r62412 | mark.dickinson | 2008-04-20 03:22:30 +0200 (Sun, 20 Apr 2008) | 5 lines Report additional diagnostic information in test_math, to help track down debian-alpha buildbot failure. ........ r62413 | mark.dickinson | 2008-04-20 03:39:24 +0200 (Sun, 20 Apr 2008) | 3 lines FreeBSD doesn't follow C99 for modf(inf); so add explicit special-value handling to math.modf code. ........ r62414 | mark.dickinson | 2008-04-20 06:13:13 +0200 (Sun, 20 Apr 2008) | 5 lines Yet more explicit special case handling to make math.pow behave on alpha Tru64. All IEEE 754 special values are now handled directly; only the finite**finite case is handled by libm. ........ r62418 | mark.dickinson | 2008-04-20 18:13:17 +0200 (Sun, 20 Apr 2008) | 7 lines Issue 2662: Initialize special value tables dynamically (i.e. when cmath module is loaded) instead of statically. This fixes compile-time problems on platforms where HUGE_VAL is an extern variable rather than a constant. Thanks Hirokazu Yamamoto for the patch. ........ r62419 | andrew.kuchling | 2008-04-20 18:54:02 +0200 (Sun, 20 Apr 2008) | 1 line Move description of math module changes; various edits to description of cmath changes ........
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.. method:: Popen.send_signal(signal)
Sends the signal *signal* to the child.
.. note::
On Windows, SIGTERM is an alias for :meth:`terminate`. CTRL_C_EVENT and
CTRL_BREAK_EVENT can be sent to processes started with a *creationflags*
parameter which includes `CREATE_NEW_PROCESS_GROUP`.
Merged revisions 62386-62387,62389-62393,62396,62400-62402,62407,62409-62410,62412-62414,62418-62419 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r62386 | christian.heimes | 2008-04-19 04:23:57 +0200 (Sat, 19 Apr 2008) | 2 lines Added kill, terminate and send_signal to subprocess.Popen The bits and pieces for the Windows side were already in place. The POSIX side is trivial (as usual) and uses os.kill(). ........ r62387 | georg.brandl | 2008-04-19 10:23:59 +0200 (Sat, 19 Apr 2008) | 2 lines Fix-up docs for revision 62386. ........ r62389 | georg.brandl | 2008-04-19 18:57:43 +0200 (Sat, 19 Apr 2008) | 2 lines #2369: clarify that copyfile() doesn't take a target directory. ........ r62390 | georg.brandl | 2008-04-19 18:58:28 +0200 (Sat, 19 Apr 2008) | 2 lines #2634: clarify meaning of env parameter to spawn/exec*e. ........ r62391 | georg.brandl | 2008-04-19 18:58:49 +0200 (Sat, 19 Apr 2008) | 2 lines #2633: clarify meaning of env parameter. ........ r62392 | georg.brandl | 2008-04-19 18:59:16 +0200 (Sat, 19 Apr 2008) | 2 lines #2631: clarify IMPORT_NAME semantics. ........ r62393 | georg.brandl | 2008-04-19 19:00:14 +0200 (Sat, 19 Apr 2008) | 2 lines :func: et al. should *not* include the parens. ........ r62396 | mark.dickinson | 2008-04-19 20:51:48 +0200 (Sat, 19 Apr 2008) | 5 lines Additional tests for math.pow, and extra special-case handling code in math.pow, in the hope of making all tests pass on the alpha Tru64 buildbot. ........ r62400 | mark.dickinson | 2008-04-19 21:41:52 +0200 (Sat, 19 Apr 2008) | 3 lines Additional special-case handling for math.pow. Windows/VS2008 doesn't like (-1)**(+-inf). ........ r62401 | benjamin.peterson | 2008-04-19 21:47:34 +0200 (Sat, 19 Apr 2008) | 2 lines Complete documentation for errors argument of io's open and TextIOWrapper ........ r62402 | mark.dickinson | 2008-04-19 22:31:16 +0200 (Sat, 19 Apr 2008) | 2 lines Document updates to math and cmath modules. ........ r62407 | georg.brandl | 2008-04-19 23:28:38 +0200 (Sat, 19 Apr 2008) | 2 lines Update template for newest Sphinx. ........ r62409 | mark.dickinson | 2008-04-19 23:35:35 +0200 (Sat, 19 Apr 2008) | 5 lines Correct documentation for math.pow; 0**nan is nan, not 0. (But nan**0 and 1**nan are 1.) Also fix minor typo: 'quite NaN' -> 'quiet NaN' ........ r62410 | mark.dickinson | 2008-04-19 23:49:22 +0200 (Sat, 19 Apr 2008) | 4 lines Move asinh documentation to the proper place. Remove meaningless 'in radians' from inverse hyperbolic functions. ........ r62412 | mark.dickinson | 2008-04-20 03:22:30 +0200 (Sun, 20 Apr 2008) | 5 lines Report additional diagnostic information in test_math, to help track down debian-alpha buildbot failure. ........ r62413 | mark.dickinson | 2008-04-20 03:39:24 +0200 (Sun, 20 Apr 2008) | 3 lines FreeBSD doesn't follow C99 for modf(inf); so add explicit special-value handling to math.modf code. ........ r62414 | mark.dickinson | 2008-04-20 06:13:13 +0200 (Sun, 20 Apr 2008) | 5 lines Yet more explicit special case handling to make math.pow behave on alpha Tru64. All IEEE 754 special values are now handled directly; only the finite**finite case is handled by libm. ........ r62418 | mark.dickinson | 2008-04-20 18:13:17 +0200 (Sun, 20 Apr 2008) | 7 lines Issue 2662: Initialize special value tables dynamically (i.e. when cmath module is loaded) instead of statically. This fixes compile-time problems on platforms where HUGE_VAL is an extern variable rather than a constant. Thanks Hirokazu Yamamoto for the patch. ........ r62419 | andrew.kuchling | 2008-04-20 18:54:02 +0200 (Sun, 20 Apr 2008) | 1 line Move description of math module changes; various edits to description of cmath changes ........
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.. method:: Popen.terminate()
Stop the child. On Posix OSs the method sends SIGTERM to the
child. On Windows the Win32 API function :c:func:`TerminateProcess` is called
Merged revisions 62386-62387,62389-62393,62396,62400-62402,62407,62409-62410,62412-62414,62418-62419 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r62386 | christian.heimes | 2008-04-19 04:23:57 +0200 (Sat, 19 Apr 2008) | 2 lines Added kill, terminate and send_signal to subprocess.Popen The bits and pieces for the Windows side were already in place. The POSIX side is trivial (as usual) and uses os.kill(). ........ r62387 | georg.brandl | 2008-04-19 10:23:59 +0200 (Sat, 19 Apr 2008) | 2 lines Fix-up docs for revision 62386. ........ r62389 | georg.brandl | 2008-04-19 18:57:43 +0200 (Sat, 19 Apr 2008) | 2 lines #2369: clarify that copyfile() doesn't take a target directory. ........ r62390 | georg.brandl | 2008-04-19 18:58:28 +0200 (Sat, 19 Apr 2008) | 2 lines #2634: clarify meaning of env parameter to spawn/exec*e. ........ r62391 | georg.brandl | 2008-04-19 18:58:49 +0200 (Sat, 19 Apr 2008) | 2 lines #2633: clarify meaning of env parameter. ........ r62392 | georg.brandl | 2008-04-19 18:59:16 +0200 (Sat, 19 Apr 2008) | 2 lines #2631: clarify IMPORT_NAME semantics. ........ r62393 | georg.brandl | 2008-04-19 19:00:14 +0200 (Sat, 19 Apr 2008) | 2 lines :func: et al. should *not* include the parens. ........ r62396 | mark.dickinson | 2008-04-19 20:51:48 +0200 (Sat, 19 Apr 2008) | 5 lines Additional tests for math.pow, and extra special-case handling code in math.pow, in the hope of making all tests pass on the alpha Tru64 buildbot. ........ r62400 | mark.dickinson | 2008-04-19 21:41:52 +0200 (Sat, 19 Apr 2008) | 3 lines Additional special-case handling for math.pow. Windows/VS2008 doesn't like (-1)**(+-inf). ........ r62401 | benjamin.peterson | 2008-04-19 21:47:34 +0200 (Sat, 19 Apr 2008) | 2 lines Complete documentation for errors argument of io's open and TextIOWrapper ........ r62402 | mark.dickinson | 2008-04-19 22:31:16 +0200 (Sat, 19 Apr 2008) | 2 lines Document updates to math and cmath modules. ........ r62407 | georg.brandl | 2008-04-19 23:28:38 +0200 (Sat, 19 Apr 2008) | 2 lines Update template for newest Sphinx. ........ r62409 | mark.dickinson | 2008-04-19 23:35:35 +0200 (Sat, 19 Apr 2008) | 5 lines Correct documentation for math.pow; 0**nan is nan, not 0. (But nan**0 and 1**nan are 1.) Also fix minor typo: 'quite NaN' -> 'quiet NaN' ........ r62410 | mark.dickinson | 2008-04-19 23:49:22 +0200 (Sat, 19 Apr 2008) | 4 lines Move asinh documentation to the proper place. Remove meaningless 'in radians' from inverse hyperbolic functions. ........ r62412 | mark.dickinson | 2008-04-20 03:22:30 +0200 (Sun, 20 Apr 2008) | 5 lines Report additional diagnostic information in test_math, to help track down debian-alpha buildbot failure. ........ r62413 | mark.dickinson | 2008-04-20 03:39:24 +0200 (Sun, 20 Apr 2008) | 3 lines FreeBSD doesn't follow C99 for modf(inf); so add explicit special-value handling to math.modf code. ........ r62414 | mark.dickinson | 2008-04-20 06:13:13 +0200 (Sun, 20 Apr 2008) | 5 lines Yet more explicit special case handling to make math.pow behave on alpha Tru64. All IEEE 754 special values are now handled directly; only the finite**finite case is handled by libm. ........ r62418 | mark.dickinson | 2008-04-20 18:13:17 +0200 (Sun, 20 Apr 2008) | 7 lines Issue 2662: Initialize special value tables dynamically (i.e. when cmath module is loaded) instead of statically. This fixes compile-time problems on platforms where HUGE_VAL is an extern variable rather than a constant. Thanks Hirokazu Yamamoto for the patch. ........ r62419 | andrew.kuchling | 2008-04-20 18:54:02 +0200 (Sun, 20 Apr 2008) | 1 line Move description of math module changes; various edits to description of cmath changes ........
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to stop the child.
.. method:: Popen.kill()
Kills the child. On Posix OSs the function sends SIGKILL to the child.
On Windows :meth:`kill` is an alias for :meth:`terminate`.
The following attributes are also available:
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Merged revisions 65437,65469,65476,65480,65502,65528,65539,65543,65558,65561-65562,65565,65591,65601,65608,65610,65639 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r65437 | georg.brandl | 2008-08-03 22:28:55 +0000 (Sun, 03 Aug 2008) | 2 lines Note the removal of several committers. ........ r65469 | gregory.p.smith | 2008-08-04 01:03:50 +0000 (Mon, 04 Aug 2008) | 3 lines issue1606: Add warnings to the subprocess documentation about common pitfalls of using pipes that cause deadlocks. ........ r65476 | georg.brandl | 2008-08-04 06:29:36 +0000 (Mon, 04 Aug 2008) | 2 lines Fix markup. ........ r65480 | georg.brandl | 2008-08-04 07:31:50 +0000 (Mon, 04 Aug 2008) | 3 lines Clarify the meaning of the select() parameters and sync names with docstring. ........ r65502 | gregory.p.smith | 2008-08-04 18:34:07 +0000 (Mon, 04 Aug 2008) | 2 lines more cleanup ups of the recently added warnings in the subprocess docs. ........ r65528 | brett.cannon | 2008-08-04 21:52:25 +0000 (Mon, 04 Aug 2008) | 4 lines Add a note about all the modules/packages changed to silence -3 warnings. More changes are needed once some decisions are made, but this is the work up to this point. ........ r65539 | andrew.kuchling | 2008-08-05 01:38:08 +0000 (Tue, 05 Aug 2008) | 6 lines #3367 from Kristjan Valur Jonsson: If a PyTokenizer_FromString() is called with an empty string, the tokenizer's line_start member never gets initialized. Later, it is compared with the token pointer 'a' in parsetok.c:193 and that behavior can result in undefined behavior. ........ r65543 | andrew.kuchling | 2008-08-05 02:05:23 +0000 (Tue, 05 Aug 2008) | 1 line #3367: revert rev. 65539: this change causes test_parser to fail ........ r65558 | georg.brandl | 2008-08-06 17:20:41 +0000 (Wed, 06 Aug 2008) | 2 lines Fix longstringitem definition. #3505. ........ r65561 | mark.dickinson | 2008-08-06 20:12:30 +0000 (Wed, 06 Aug 2008) | 2 lines Docstring typo ........ r65562 | mark.dickinson | 2008-08-06 21:36:57 +0000 (Wed, 06 Aug 2008) | 2 lines Remove duplicate import ........ r65565 | andrew.kuchling | 2008-08-07 01:47:34 +0000 (Thu, 07 Aug 2008) | 1 line Add some items ........ r65591 | georg.brandl | 2008-08-08 06:42:20 +0000 (Fri, 08 Aug 2008) | 2 lines #3519: callee is an expression too. ........ r65601 | georg.brandl | 2008-08-08 15:34:34 +0000 (Fri, 08 Aug 2008) | 2 lines Remove mention of backquotes in the tutorial. ........ r65608 | guido.van.rossum | 2008-08-09 14:55:34 +0000 (Sat, 09 Aug 2008) | 2 lines Add news item about _sre.compile() re-bytecode validator. ........ r65610 | antoine.pitrou | 2008-08-09 17:27:23 +0000 (Sat, 09 Aug 2008) | 3 lines move NEWS entry to the appropriate section (oops!) ........ r65639 | georg.brandl | 2008-08-11 10:27:31 +0000 (Mon, 11 Aug 2008) | 2 lines #3540: fix exception name. ........
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.. warning::
Use :meth:`communicate` rather than :attr:`.stdin.write <stdin>`,
:attr:`.stdout.read <stdout>` or :attr:`.stderr.read <stderr>` to avoid
deadlocks due to any of the other OS pipe buffers filling up and blocking the
child process.
Merged revisions 65437,65469,65476,65480,65502,65528,65539,65543,65558,65561-65562,65565,65591,65601,65608,65610,65639 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r65437 | georg.brandl | 2008-08-03 22:28:55 +0000 (Sun, 03 Aug 2008) | 2 lines Note the removal of several committers. ........ r65469 | gregory.p.smith | 2008-08-04 01:03:50 +0000 (Mon, 04 Aug 2008) | 3 lines issue1606: Add warnings to the subprocess documentation about common pitfalls of using pipes that cause deadlocks. ........ r65476 | georg.brandl | 2008-08-04 06:29:36 +0000 (Mon, 04 Aug 2008) | 2 lines Fix markup. ........ r65480 | georg.brandl | 2008-08-04 07:31:50 +0000 (Mon, 04 Aug 2008) | 3 lines Clarify the meaning of the select() parameters and sync names with docstring. ........ r65502 | gregory.p.smith | 2008-08-04 18:34:07 +0000 (Mon, 04 Aug 2008) | 2 lines more cleanup ups of the recently added warnings in the subprocess docs. ........ r65528 | brett.cannon | 2008-08-04 21:52:25 +0000 (Mon, 04 Aug 2008) | 4 lines Add a note about all the modules/packages changed to silence -3 warnings. More changes are needed once some decisions are made, but this is the work up to this point. ........ r65539 | andrew.kuchling | 2008-08-05 01:38:08 +0000 (Tue, 05 Aug 2008) | 6 lines #3367 from Kristjan Valur Jonsson: If a PyTokenizer_FromString() is called with an empty string, the tokenizer's line_start member never gets initialized. Later, it is compared with the token pointer 'a' in parsetok.c:193 and that behavior can result in undefined behavior. ........ r65543 | andrew.kuchling | 2008-08-05 02:05:23 +0000 (Tue, 05 Aug 2008) | 1 line #3367: revert rev. 65539: this change causes test_parser to fail ........ r65558 | georg.brandl | 2008-08-06 17:20:41 +0000 (Wed, 06 Aug 2008) | 2 lines Fix longstringitem definition. #3505. ........ r65561 | mark.dickinson | 2008-08-06 20:12:30 +0000 (Wed, 06 Aug 2008) | 2 lines Docstring typo ........ r65562 | mark.dickinson | 2008-08-06 21:36:57 +0000 (Wed, 06 Aug 2008) | 2 lines Remove duplicate import ........ r65565 | andrew.kuchling | 2008-08-07 01:47:34 +0000 (Thu, 07 Aug 2008) | 1 line Add some items ........ r65591 | georg.brandl | 2008-08-08 06:42:20 +0000 (Fri, 08 Aug 2008) | 2 lines #3519: callee is an expression too. ........ r65601 | georg.brandl | 2008-08-08 15:34:34 +0000 (Fri, 08 Aug 2008) | 2 lines Remove mention of backquotes in the tutorial. ........ r65608 | guido.van.rossum | 2008-08-09 14:55:34 +0000 (Sat, 09 Aug 2008) | 2 lines Add news item about _sre.compile() re-bytecode validator. ........ r65610 | antoine.pitrou | 2008-08-09 17:27:23 +0000 (Sat, 09 Aug 2008) | 3 lines move NEWS entry to the appropriate section (oops!) ........ r65639 | georg.brandl | 2008-08-11 10:27:31 +0000 (Mon, 11 Aug 2008) | 2 lines #3540: fix exception name. ........
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.. attribute:: Popen.stdin
If the *stdin* argument was :data:`PIPE`, this attribute is a :term:`file
object` that provides input to the child process. Otherwise, it is ``None``.
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.. attribute:: Popen.stdout
If the *stdout* argument was :data:`PIPE`, this attribute is a :term:`file
object` that provides output from the child process. Otherwise, it is ``None``.
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.. attribute:: Popen.stderr
If the *stderr* argument was :data:`PIPE`, this attribute is a :term:`file
object` that provides error output from the child process. Otherwise, it is
Merged revisions 67531-67532,67538,67553-67554,67556-67557,67571,67574-67575,67579-67580,67591,67597,67608,67631 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r67531 | georg.brandl | 2008-12-04 19:54:05 +0100 (Thu, 04 Dec 2008) | 2 lines Add reference to enumerate() to indices example. ........ r67532 | georg.brandl | 2008-12-04 19:59:16 +0100 (Thu, 04 Dec 2008) | 2 lines Add another heapq example. ........ r67538 | georg.brandl | 2008-12-04 22:28:16 +0100 (Thu, 04 Dec 2008) | 2 lines Clarification to avoid confusing output with file descriptors. ........ r67553 | georg.brandl | 2008-12-05 08:49:49 +0100 (Fri, 05 Dec 2008) | 2 lines #4408: document regex.groups. ........ r67554 | georg.brandl | 2008-12-05 08:52:26 +0100 (Fri, 05 Dec 2008) | 2 lines #4409: fix asterisks looking like footnotes. ........ r67556 | georg.brandl | 2008-12-05 09:02:17 +0100 (Fri, 05 Dec 2008) | 2 lines #4441: improve doc for os.open() flags. ........ r67557 | georg.brandl | 2008-12-05 09:06:57 +0100 (Fri, 05 Dec 2008) | 2 lines Add an index entry for "subclassing immutable types". ........ r67571 | georg.brandl | 2008-12-05 10:13:45 +0100 (Fri, 05 Dec 2008) | 2 lines Use markup. ........ r67574 | georg.brandl | 2008-12-05 10:25:32 +0100 (Fri, 05 Dec 2008) | 2 lines #4441 followup: Add link to open() docs for Windows. ........ r67575 | georg.brandl | 2008-12-05 12:34:51 +0100 (Fri, 05 Dec 2008) | 2 lines #4544: add `dedent` to textwrap.__all__. ........ r67579 | georg.brandl | 2008-12-05 16:29:39 +0100 (Fri, 05 Dec 2008) | 2 lines #4517: add "special method" glossary entry and clarify when __getattribute__ is bypassed. ........ r67580 | georg.brandl | 2008-12-05 16:32:29 +0100 (Fri, 05 Dec 2008) | 2 lines #4478: document that copyfile() can raise Error. ........ r67591 | georg.brandl | 2008-12-05 19:00:06 +0100 (Fri, 05 Dec 2008) | 2 lines Followup to #4511: add link from decorator glossary entry to definition. ........ r67597 | georg.brandl | 2008-12-05 20:03:19 +0100 (Fri, 05 Dec 2008) | 2 lines Remove confusing sentence part. ........ r67608 | georg.brandl | 2008-12-06 12:57:12 +0100 (Sat, 06 Dec 2008) | 2 lines Follow-up to #4488: document PIPE and STDOUT properly. ........ r67631 | georg.brandl | 2008-12-07 12:54:07 +0100 (Sun, 07 Dec 2008) | 2 lines Add link to the favicon to the docs. ........
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``None``.
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.. attribute:: Popen.pid
The process ID of the child process.
Note that if you set the *shell* argument to ``True``, this is the process ID
of the spawned shell.
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.. attribute:: Popen.returncode
The child return code, set by :meth:`poll` and :meth:`wait` (and indirectly
by :meth:`communicate`). A ``None`` value indicates that the process
hasn't terminated yet.
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A negative value ``-N`` indicates that the child was terminated by signal
``N`` (Unix only).
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Windows Popen Helpers
---------------------
The :class:`STARTUPINFO` class and following constants are only available
on Windows.
.. class:: STARTUPINFO()
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Partial support of the Windows
`STARTUPINFO <http://msdn.microsoft.com/en-us/library/ms686331(v=vs.85).aspx>`__
structure is used for :class:`Popen` creation.
.. attribute:: dwFlags
A bit field that determines whether certain :class:`STARTUPINFO`
attributes are used when the process creates a window. ::
si = subprocess.STARTUPINFO()
si.dwFlags = subprocess.STARTF_USESTDHANDLES | subprocess.STARTF_USESHOWWINDOW
.. attribute:: hStdInput
If :attr:`dwFlags` specifies :data:`STARTF_USESTDHANDLES`, this attribute
is the standard input handle for the process. If
:data:`STARTF_USESTDHANDLES` is not specified, the default for standard
input is the keyboard buffer.
.. attribute:: hStdOutput
If :attr:`dwFlags` specifies :data:`STARTF_USESTDHANDLES`, this attribute
is the standard output handle for the process. Otherwise, this attribute
is ignored and the default for standard output is the console window's
buffer.
.. attribute:: hStdError
If :attr:`dwFlags` specifies :data:`STARTF_USESTDHANDLES`, this attribute
is the standard error handle for the process. Otherwise, this attribute is
ignored and the default for standard error is the console window's buffer.
.. attribute:: wShowWindow
If :attr:`dwFlags` specifies :data:`STARTF_USESHOWWINDOW`, this attribute
can be any of the values that can be specified in the ``nCmdShow``
parameter for the
`ShowWindow <http://msdn.microsoft.com/en-us/library/ms633548(v=vs.85).aspx>`__
function, except for ``SW_SHOWDEFAULT``. Otherwise, this attribute is
ignored.
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:data:`SW_HIDE` is provided for this attribute. It is used when
:class:`Popen` is called with ``shell=True``.
Constants
^^^^^^^^^
The :mod:`subprocess` module exposes the following constants.
.. data:: STD_INPUT_HANDLE
The standard input device. Initially, this is the console input buffer,
``CONIN$``.
.. data:: STD_OUTPUT_HANDLE
The standard output device. Initially, this is the active console screen
buffer, ``CONOUT$``.
.. data:: STD_ERROR_HANDLE
The standard error device. Initially, this is the active console screen
buffer, ``CONOUT$``.
.. data:: SW_HIDE
Hides the window. Another window will be activated.
.. data:: STARTF_USESTDHANDLES
Specifies that the :attr:`STARTUPINFO.hStdInput`,
:attr:`STARTUPINFO.hStdOutput`, and :attr:`STARTUPINFO.hStdError` attributes
contain additional information.
.. data:: STARTF_USESHOWWINDOW
Specifies that the :attr:`STARTUPINFO.wShowWindow` attribute contains
additional information.
.. data:: CREATE_NEW_CONSOLE
The new process has a new console, instead of inheriting its parent's
console (the default).
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This flag is always set when :class:`Popen` is created with ``shell=True``.
.. data:: CREATE_NEW_PROCESS_GROUP
A :class:`Popen` ``creationflags`` parameter to specify that a new process
group will be created. This flag is necessary for using :func:`os.kill`
on the subprocess.
This flag is ignored if :data:`CREATE_NEW_CONSOLE` is specified.
Merged revisions 64434-64435,64440-64443,64445,64447-64448,64450,64452,64455,64461,64464,64466,64468 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r64434 | andrew.kuchling | 2008-06-20 18:13:58 -0500 (Fri, 20 Jun 2008) | 1 line Remove request for e-mail; it's unlikely these classes will be saved ........ r64435 | andrew.kuchling | 2008-06-20 18:14:32 -0500 (Fri, 20 Jun 2008) | 1 line Grammar fixes ........ r64440 | andrew.kuchling | 2008-06-21 08:29:12 -0500 (Sat, 21 Jun 2008) | 1 line Docstring typo ........ r64441 | andrew.kuchling | 2008-06-21 08:47:20 -0500 (Sat, 21 Jun 2008) | 1 line Use repr() for bad input strings; this makes the empty string or binary characters more visible ........ r64442 | andrew.kuchling | 2008-06-21 08:48:38 -0500 (Sat, 21 Jun 2008) | 1 line Docstring correction ........ r64443 | georg.brandl | 2008-06-21 09:26:19 -0500 (Sat, 21 Jun 2008) | 2 lines Documentation fix. ........ r64445 | facundo.batista | 2008-06-21 12:30:06 -0500 (Sat, 21 Jun 2008) | 3 lines Reviewed and updated the documentation. Fixes #3017. ........ r64447 | facundo.batista | 2008-06-21 13:58:04 -0500 (Sat, 21 Jun 2008) | 6 lines Now a from submitted via POST that also has a query string will contain both FieldStorage and MiniFieldStorage items. Fixes #1817. ........ r64448 | facundo.batista | 2008-06-21 14:48:19 -0500 (Sat, 21 Jun 2008) | 5 lines In the deprecated functions I added an alert to review specially a section of the subprocess documentation that helps with the replacing of those functionss. ........ r64450 | georg.brandl | 2008-06-22 04:05:29 -0500 (Sun, 22 Jun 2008) | 2 lines Turn section references into proper cross-references. ........ r64452 | facundo.batista | 2008-06-22 08:36:20 -0500 (Sun, 22 Jun 2008) | 5 lines Issue #2722. Now the char buffer to support the path string has not fixed length, it mallocs memory if needed. As a result, we don't have a maximum for the getcwd() method. ........ r64455 | facundo.batista | 2008-06-22 10:27:10 -0500 (Sun, 22 Jun 2008) | 4 lines Issue 3164. Small fix to don't repeat a comparation without necessity. ........ r64461 | georg.brandl | 2008-06-22 13:11:52 -0500 (Sun, 22 Jun 2008) | 2 lines #3085: Fix syntax error. ........ r64464 | georg.brandl | 2008-06-22 13:31:54 -0500 (Sun, 22 Jun 2008) | 2 lines Expand docstrings of sqlite3 functions. ........ r64466 | georg.brandl | 2008-06-22 14:07:59 -0500 (Sun, 22 Jun 2008) | 2 lines Write out "phi" consistently. ........ r64468 | facundo.batista | 2008-06-22 14:35:24 -0500 (Sun, 22 Jun 2008) | 4 lines Just returning nothing instead of rising TestSkipped, because it makes the test fail in the trunk.loewis-sun buildbot. ........
2008-07-02 14:30:14 -03:00
.. _subprocess-replacements:
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Replacing Older Functions with the subprocess Module
----------------------------------------------------
In this section, "a becomes b" means that b can be used as a replacement for a.
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.. note::
All "a" functions in this section fail (more or less) silently if the
executed program cannot be found; the "b" replacements raise :exc:`OSError`
instead.
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In addition, the replacements using :func:`check_output` will fail with a
:exc:`CalledProcessError` if the requested operation produces a non-zero
return code. The output is still available as the ``output`` attribute of
the raised exception.
In the following examples, we assume that the relevant functions have already
been imported from the subprocess module.
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Replacing /bin/sh shell backquote
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
::
output=`mycmd myarg`
# becomes
output = check_output(["mycmd", "myarg"])
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2008-10-10 21:49:57 -03:00
Replacing shell pipeline
^^^^^^^^^^^^^^^^^^^^^^^^
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::
output=`dmesg | grep hda`
# becomes
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p1 = Popen(["dmesg"], stdout=PIPE)
p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
p1.stdout.close() # Allow p1 to receive a SIGPIPE if p2 exits.
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output = p2.communicate()[0]
The p1.stdout.close() call after starting the p2 is important in order for p1
to receive a SIGPIPE if p2 exits before p1.
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Alternatively, for trusted input, the shell's own pipeline support may still
be used directly:
output=`dmesg | grep hda`
# becomes
output=check_output("dmesg | grep hda", shell=True)
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
Replacing :func:`os.system`
^^^^^^^^^^^^^^^^^^^^^^^^^^^
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::
sts = os.system("mycmd" + " myarg")
# becomes
sts = call("mycmd" + " myarg", shell=True)
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Notes:
* Calling the program through the shell is usually not required.
A more realistic example would look like this::
try:
retcode = call("mycmd" + " myarg", shell=True)
if retcode < 0:
print("Child was terminated by signal", -retcode, file=sys.stderr)
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else:
print("Child returned", retcode, file=sys.stderr)
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except OSError as e:
print("Execution failed:", e, file=sys.stderr)
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Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
Replacing the :func:`os.spawn <os.spawnl>` family
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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P_NOWAIT example::
pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
==>
pid = Popen(["/bin/mycmd", "myarg"]).pid
P_WAIT example::
retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
==>
retcode = call(["/bin/mycmd", "myarg"])
Vector example::
os.spawnvp(os.P_NOWAIT, path, args)
==>
Popen([path] + args[1:])
Environment example::
os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
==>
Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
Replacing :func:`os.popen`, :func:`os.popen2`, :func:`os.popen3`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2007-08-15 11:28:22 -03:00
::
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
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(child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize)
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==>
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
p = Popen(cmd, shell=True, bufsize=bufsize,
stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdin, child_stdout) = (p.stdin, p.stdout)
2007-08-15 11:28:22 -03:00
::
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
(child_stdin,
child_stdout,
child_stderr) = os.popen3(cmd, mode, bufsize)
==>
p = Popen(cmd, shell=True, bufsize=bufsize,
stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
(child_stdin,
child_stdout,
child_stderr) = (p.stdin, p.stdout, p.stderr)
::
(child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize)
==>
p = Popen(cmd, shell=True, bufsize=bufsize,
stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
(child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout)
Return code handling translates as follows::
pipe = os.popen(cmd, 'w')
...
rc = pipe.close()
2010-07-14 07:16:11 -03:00
if rc is not None and rc >> 8:
print("There were some errors")
2007-08-15 11:28:22 -03:00
==>
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
process = Popen(cmd, 'w', stdin=PIPE)
...
process.stdin.close()
if process.wait() != 0:
print("There were some errors")
Merged revisions 73196,73278-73280,73299,73308,73312-73313,73317-73318,73321,73324,73331,73335,73340,73363 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r73196 | benjamin.peterson | 2009-06-03 20:40:29 -0500 (Wed, 03 Jun 2009) | 1 line use the offical api ........ r73278 | benjamin.peterson | 2009-06-07 17:33:11 -0500 (Sun, 07 Jun 2009) | 1 line inherit from object ........ r73279 | benjamin.peterson | 2009-06-07 17:35:00 -0500 (Sun, 07 Jun 2009) | 1 line always inherit from an appropiate base class ........ r73280 | benjamin.peterson | 2009-06-07 17:54:35 -0500 (Sun, 07 Jun 2009) | 1 line use booleans for flags ........ r73299 | georg.brandl | 2009-06-08 13:41:36 -0500 (Mon, 08 Jun 2009) | 1 line Typo fix. ........ r73308 | benjamin.peterson | 2009-06-08 17:18:32 -0500 (Mon, 08 Jun 2009) | 1 line remove useless assertion ........ r73312 | benjamin.peterson | 2009-06-08 18:44:13 -0500 (Mon, 08 Jun 2009) | 1 line remove error checks already done in set_context() ........ r73313 | r.david.murray | 2009-06-08 19:44:22 -0500 (Mon, 08 Jun 2009) | 4 lines Issue 2947: document how return code handling translates from os.popen to subprocess. Also fixes reference link in the os.spawn documentation. ........ r73317 | benjamin.peterson | 2009-06-09 12:24:26 -0500 (Tue, 09 Jun 2009) | 1 line make ast.c depend on the grammar ........ r73318 | benjamin.peterson | 2009-06-09 12:29:51 -0500 (Tue, 09 Jun 2009) | 1 line explain why keyword names are not just NAME ........ r73321 | benjamin.peterson | 2009-06-09 16:13:43 -0500 (Tue, 09 Jun 2009) | 1 line update symbol.py from with statement changes ........ r73324 | amaury.forgeotdarc | 2009-06-09 17:53:16 -0500 (Tue, 09 Jun 2009) | 2 lines Avoid invoking the parser/compiler just to test the presence of a function. ........ r73331 | benjamin.peterson | 2009-06-10 08:45:31 -0500 (Wed, 10 Jun 2009) | 1 line fix spelling ........ r73335 | raymond.hettinger | 2009-06-10 11:15:40 -0500 (Wed, 10 Jun 2009) | 1 line Fix signed/unsigned compiler warning. ........ r73340 | amaury.forgeotdarc | 2009-06-10 15:30:19 -0500 (Wed, 10 Jun 2009) | 2 lines Fix a typo spotted by Nick Coghlan. ........ r73363 | benjamin.peterson | 2009-06-11 12:51:17 -0500 (Thu, 11 Jun 2009) | 1 line use multi-with syntax ........
2009-06-11 19:54:11 -03:00
Replacing functions from the :mod:`popen2` module
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. note::
If the cmd argument to popen2 functions is a string, the command is executed
through /bin/sh. If it is a list, the command is directly executed.
::
(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
==>
p = Popen(["somestring"], shell=True, bufsize=bufsize,
stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
::
(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
==>
p = Popen(["mycmd", "myarg"], bufsize=bufsize,
stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
:class:`popen2.Popen3` and :class:`popen2.Popen4` basically work as
:class:`subprocess.Popen`, except that:
* :class:`Popen` raises an exception if the execution fails.
* the *capturestderr* argument is replaced with the *stderr* argument.
* ``stdin=PIPE`` and ``stdout=PIPE`` must be specified.
* popen2 closes all file descriptors by default, but you have to specify
``close_fds=True`` with :class:`Popen` to guarantee this behavior on
all platforms or past Python versions.
Legacy Shell Invocation Functions
---------------------------------
This module also provides the following legacy functions from the 2.x
``commands`` module. These operations implicitly invoke the system shell and
none of the guarantees described above regarding security and exception
handling consistency are valid for these functions.
.. function:: getstatusoutput(cmd)
Return ``(status, output)`` of executing *cmd* in a shell.
Execute the string *cmd* in a shell with :func:`os.popen` and return a 2-tuple
``(status, output)``. *cmd* is actually run as ``{ cmd ; } 2>&1``, so that the
returned output will contain output or error messages. A trailing newline is
stripped from the output. The exit status for the command can be interpreted
according to the rules for the C function :c:func:`wait`. Example::
>>> subprocess.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> subprocess.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> subprocess.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
Availability: UNIX.
.. function:: getoutput(cmd)
Return output (stdout and stderr) of executing *cmd* in a shell.
Like :func:`getstatusoutput`, except the exit status is ignored and the return
value is a string containing the command's output. Example::
>>> subprocess.getoutput('ls /bin/ls')
'/bin/ls'
Availability: UNIX.
Notes
-----
.. _converting-argument-sequence:
Converting an argument sequence to a string on Windows
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Windows, an *args* sequence is converted to a string that can be parsed
using the following rules (which correspond to the rules used by 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.