From 3fa8fe7177bb941aa60ecaf14d1fa1750a26f674 Mon Sep 17 00:00:00 2001 From: richardhob Date: Thu, 19 Jan 2023 23:56:13 -0800 Subject: [PATCH] gh-88324: Clarify documentation for redirected stdout/stderr when using subprocess in Linux (#94035) * Update description of stdout, stderr, and stdin. Changes: - Move the ``None`` option (which is default) to the front of the list of input options - Move the ``None`` option description up to make the default behavior more clear (No redirection) - Remove mention of Child File Descriptors from ``None`` option description --- Doc/library/subprocess.rst | 32 +++++++++---------- Misc/ACKS | 1 + ...2-06-19-22-04-47.gh-issue-88324.GHhSQ1.rst | 3 ++ 3 files changed, 19 insertions(+), 17 deletions(-) create mode 100644 Misc/NEWS.d/next/Documentation/2022-06-19-22-04-47.gh-issue-88324.GHhSQ1.rst diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst index e4e38e93368..785251afdf2 100644 --- a/Doc/library/subprocess.rst +++ b/Doc/library/subprocess.rst @@ -270,15 +270,14 @@ default values. The arguments that are most commonly needed are: *stdin*, *stdout* and *stderr* specify the executed program's standard input, standard output and standard error file handles, respectively. Valid values - are :data:`PIPE`, :data:`DEVNULL`, an existing file descriptor (a positive - integer), an existing file object with a valid file descriptor, and ``None``. - :data:`PIPE` indicates that a new pipe to the child should be created. - :data:`DEVNULL` indicates that the special file :data:`os.devnull` will - be used. 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*. + are ``None``, :data:`PIPE`, :data:`DEVNULL`, an existing file descriptor (a + positive integer), and an existing :term:`file object` with a valid file + descriptor. With the default settings of ``None``, no redirection will + occur. :data:`PIPE` indicates that a new pipe to the child should be + created. :data:`DEVNULL` indicates that the special file :data:`os.devnull` + will be used. 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*. .. index:: single: universal newlines; subprocess module @@ -490,15 +489,14 @@ functions. *stdin*, *stdout* and *stderr* specify the executed program's standard input, standard output and standard error file handles, respectively. Valid values - are :data:`PIPE`, :data:`DEVNULL`, an existing file descriptor (a positive - integer), an existing :term:`file object` with a valid file descriptor, - and ``None``. :data:`PIPE` indicates that a new pipe to the child should - be created. :data:`DEVNULL` indicates that the special file - :data:`os.devnull` will be used. 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 + are ``None``, :data:`PIPE`, :data:`DEVNULL`, an existing file descriptor (a + positive integer), and an existing :term:`file object` with a valid file + descriptor. With the default settings of ``None``, no redirection will + occur. :data:`PIPE` indicates that a new pipe to the child should be + created. :data:`DEVNULL` indicates that the special file :data:`os.devnull` + will be used. 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. + file handle as for *stdout*. If *preexec_fn* is set to a callable object, this object will be called in the child process just before the child is executed. diff --git a/Misc/ACKS b/Misc/ACKS index a51658d79fa..768034516d3 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -747,6 +747,7 @@ Aaron Hill Joel Hillacre Richie Hindle Konrad Hinsen +Richard Hoberecht David Hobley Tim Hochberg Benjamin Hodgson diff --git a/Misc/NEWS.d/next/Documentation/2022-06-19-22-04-47.gh-issue-88324.GHhSQ1.rst b/Misc/NEWS.d/next/Documentation/2022-06-19-22-04-47.gh-issue-88324.GHhSQ1.rst new file mode 100644 index 00000000000..6c8d192daa7 --- /dev/null +++ b/Misc/NEWS.d/next/Documentation/2022-06-19-22-04-47.gh-issue-88324.GHhSQ1.rst @@ -0,0 +1,3 @@ +Reword :mod:`subprocess` to emphasize default behavior of *stdin*, *stdout*, +and *stderr* arguments. Remove inaccurate statement about child file handle +inheritance.