hide command prompt when using subprocess.Popen with shell=False on Windows

[iMath]

BPO	30082
Nosy	@pfmoore, @tjguk, @zware, @eryksun, @zooba, @ohn0, @ammgws
PRs	bpo-30082 hide command prompt when using subprocess.Popen with shell=False on Windows #3013 bpo-30082 Popen: add kwarg to hide process window on Windows #19014
Files	test.py: Script to test if subprocess spawns additional windows

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-04-16.17:26:26.499>
labels = ['easy', 'type-feature', 'library', 'OS-windows', '3.11']
title = 'hide command prompt when using subprocess.Popen with shell=False on Windows'
updated_at = <Date 2021-11-09.13:15:20.475>
user = 'https://bugs.python.org/iMath'

bugs.python.org fields:

activity = <Date 2021-11-09.13:15:20.475>
actor = 'swgmma'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)', 'Windows']
creation = <Date 2017-04-16.17:26:26.499>
creator = 'iMath'
dependencies = []
files = ['48938']
hgrepos = []
issue_num = 30082
keywords = ['patch', 'easy']
message_count = 30.0
messages = ['291760', '291815', '329979', '330091', '362978', '362979', '363046', '363060', '363116', '363143', '364227', '403897', '404094', '404095', '404122', '404261', '404264', '405151', '405166', '405177', '405205', '405269', '405285', '405298', '405302', '405307', '405309', '405362', '405576', '406019']
nosy_count = 8.0
nosy_names = ['paul.moore', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'iMath', 'ohno', 'swgmma']
pr_nums = ['3013', '19014']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue30082'
versions = ['Python 3.11']

[iMath]

First, It is nearly useless for the command prompt to pop up during the running time of subprocess.Popen with shell=False.
Second, the popping up command prompt would interrupt users and do bad to user experience of GUI applications.
Third, I found QProcess within Qt won't pop up the command prompt in using.

It would be convenient to add an argument to suppress the command prompt from popping up when using subprocess.Popen with shell=False on Windows, many users are missing the feature and these are many similar feature request questions like the following
http://stackoverflow.com/questions/7006238/how-do-i-hide-the-console-when-i-use-os-system-or-subprocess-call
http://stackoverflow.com/questions/1765078/how-to-avoid-console-window-with-pyw-file-containing-os-system-call/12964900#12964900
http://stackoverflow.com/questions/1016384/cross-platform-subprocess-with-hidden-window

[eryksun]

Hiding the console is required often enough that a keyword-only parameter for this would be useful. Other platforms could simply ignore it, in contrast to writing platform-dependent code that passes startupinfo. Note that this option would also hide the window of GUI programs that do not (intentionally) ignore SW_HIDE, such as notepad.

[ohn0]

Can I work on this? I'm not sure of it's status, though.

[zooba]

Looks like it's available.

It will be a new subprocess option to not create a new window. The underlying issue is that some applications always request a console, and if your own application doesn't have one then Windows will create it. Normally you would fix this in the target application, but we can offer an option to try and force any new windows to be hidden (though as Eryk points out, it may cause unexpected behaviour and so should not be the default).

[ammgws]

I would like to pick up work on this (have started at link below), however I would like some help:

For testing purposes, could someone please provide a minimum working example of using subprocess that causes a command prompt to pop up?

I have not been able to reproduce it (using Python 3.7), though I vaguely remember encountering it in the past.

ammgws@03b9dac

[zooba]

If you use subprocess to launch any process that is marked SUBSYSTEM_CONSOLE, Windows will create a new console for it. For example, "python.exe" is such a process.

Eryk's answer in the very first StackOverflow link shows how to create a STARTUPINFO parameter with the correct settings. We just want to add a Boolean argument to subprocess.Popen.__init__() that can add that setting automatically.

[ammgws]

Sorry, perhaps I did not word it clearly. Indeed the code to implement this looks trivial, however the part I am having trouble with is reproducing the reported issue in the first place.

For example, running the attached file from a command prompt (python test.py) does not result in any additional windows popping up.

Either my test case is wrong or there is something else going on.

[zooba]

Try running that script with pythonw.exe instead.