Issue #16624: `subprocess.check_output` now accepts an `input` argument,
allowing the subprocess's stdin to be provided as a (byte) string.
Patch by Zack Weinberg.
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index 792a58f..70a21eb 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -116,7 +116,7 @@
*timeout* was added.
-.. function:: check_output(args, *, stdin=None, stderr=None, shell=False, universal_newlines=False, timeout=None)
+.. function:: check_output(args, *, input=None, stdin=None, stderr=None, shell=False, universal_newlines=False, timeout=None)
Run command with arguments and return its output.
@@ -129,15 +129,21 @@
in :ref:`frequently-used-arguments` (hence the use of keyword-only notation
in the abbreviated signature). The full function signature is largely the
same as that of the :class:`Popen` constructor - this functions passes all
- supplied arguments other than *timeout* directly through to that interface.
- In addition, *stdout* is not permitted as an argument, as it is used
- internally to collect the output from the subprocess.
+ supplied arguments other than *input* and *timeout* directly through to
+ that interface. In addition, *stdout* is not permitted as an argument, as
+ it is used internally to collect the output from the subprocess.
The *timeout* argument is passed to :meth:`Popen.wait`. If the timeout
expires, the child process will be killed and then waited for again. The
:exc:`TimeoutExpired` exception will be re-raised after the child process
has terminated.
+ The *input* argument is passed to :meth:`Popen.communicate` and thus to the
+ subprocess's stdin. If used it must be a byte sequence, or a string if
+ ``universal_newlines=True``. When used, the internal :class:`Popen` object
+ is automatically created with ``stdin=PIPE``, and the *stdin* argument may
+ not be used as well.
+
Examples::
>>> subprocess.check_output(["echo", "Hello World!"])
@@ -146,6 +152,10 @@
>>> subprocess.check_output(["echo", "Hello World!"], universal_newlines=True)
'Hello World!\n'
+ >>> subprocess.check_output(["sed", "-e", "s/foo/bar/"],
+ ... input=b"when in the course of fooman events\n")
+ b'when in the course of barman events\n'
+
>>> subprocess.check_output("exit 1", shell=True)
Traceback (most recent call last):
...
@@ -167,10 +177,6 @@
... shell=True)
'ls: non_existent_file: No such file or directory\n'
- .. versionadded:: 3.1
-
- ..
-
.. warning::
Invoking the system shell with ``shell=True`` can be a security hazard
@@ -183,9 +189,13 @@
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.
+ .. versionadded:: 3.1
+
.. versionchanged:: 3.3
*timeout* was added.
+ .. versionchanged:: 3.4
+ *input* was added.
.. data:: DEVNULL