Output of os.system, subprocess.call goes to command prompt instead of qtconsole, on Windows 10, Open Suse

Problem Description

When running os.system or subprocess.call on Windows 10, no output is produced in qtconsole. Instead the output goes to the Anaconda Prompt console or, if qtconsole was started from the start menu, is simply discarded.

The same issue is reproducible with ipython qtconsole and and the sypder IDE, where this issue was originally reported (https://github.com/spyder-ide/spyder/issues/14783), but declared an depenency issue.

When running bare-bones consoles (ipython, python), the issue does not appear, presumably because everything is displayed in the same cmd.exe window.

On OpenSuse the issue occurs likewise. If the console is started from a terminal window, that terminal will receive the output of the commands. When originally posted, I thought I couldn’t reproduce the issue on Linux.

Qt Console

As a component in Spyder

What steps reproduce the problem?

1. Run jupyter qtconsole from the Anaconda prompt.
2. In the qtconsole type import os; os.system(r"mkdir C:\tmp\demo & dir C:\tmp\demo")

What is the expected output? What do you see instead?

The expectation is to see the output in the graphical console, together with the output of print or sys.stdout.write.

Instead the output is displayed in the command prompt window.

Potentially relevant package versions

• Python version: 3.8.5
• Qt version: 5.9.7
• PyQt version: 5.9.2, PyQt5: 5.12.3
• QtConsole: 5.0.2
• OS: Windows 10, Version 2004 (OS Build 19041.804)

DEPENDENCY REPORT OF SPYDER
atomicwrites >=1.2.0            :  1.4.0 (OK)
chardet >=2.0.0                 :  4.0.0 (OK)
cloudpickle >=0.5.0             :  1.6.0 (OK)
diff_match_patch >=20181111     :  20200713 (OK)
intervaltree >=3.0.2            :  3.1.0 (OK)
IPython >=7.6.0                 :  7.20.0 (OK)
jedi =0.17.2                    :  0.17.2 (OK)
jsonschema >=3.2.0              :  3.2.0 (OK)
keyring >=17.0.0                :  22.0.1 (OK)
nbconvert >=4.0                 :  6.0.7 (OK)
numpydoc >=0.6.0                :  1.1.0 (OK)
paramiko >=2.4.0                :  2.7.2 (OK)
parso =0.7.0                    :  0.7.0 (OK)
pexpect >=4.4.0                 :  4.8.0 (OK)
pickleshare >=0.4               :  0.7.5 (OK)
psutil >=5.3                    :  5.8.0 (OK)
pygments >=2.0                  :  2.7.4 (OK)
pylint >=1.0                    :  2.6.0 (OK)
pyls >=0.36.2;<1.0.0            :  0.36.2 (OK)
pyls_black >=0.4.6              :  0.4.6 (OK)
pyls_spyder >=0.3.0             :  0.3.0 (OK)
qdarkstyle >=2.8                :  2.8.1 (OK)
qtawesome >=0.5.7               :  1.0.1 (OK)
qtconsole >=5.0.1               :  5.0.2 (OK)
qtpy >=1.5.0                    :  1.9.0 (OK)
rtree >=0.8.3                   :  0.9.4 (OK)
setuptools >=39.0.0             :  52.0.0.post20210125 (OK)
sphinx >=0.6.6                  :  3.4.3 (OK)
spyder_kernels >=1.10.1;<1.11.0 :  1.10.1 (OK)
textdistance >=4.2.0            :  4.2.1 (OK)
three_merge >=0.1.1             :  0.1.1 (OK)
watchdog >=0.10.3               :  1.0.2 (OK)
zmq >=17                        :  20.0.0 (OK)

cython >=0.21                   :  0.29.21 (OK)
matplotlib >=2.0.0              :  3.3.4 (OK)
numpy >=1.7                     :  1.19.2 (OK)
pandas >=1.1.1                  :  1.2.1 (OK)
scipy >=0.17.0                  :  1.6.0 (OK)
sympy >=0.7.3                   :  1.7.1 (OK)

[impact27]

PR spyder-ide/spyder#1478 solves that problem, but only for consoles started from spyder. Also, if another client connects to the same console, it wouldn’t recieve the messages either.

The ipython kernel creates a new sys.stdout. Any output that is written to sys.stdout or sys.stderr, for example using the print function, is sent to the client. The problem is that any non-python code is not aware of the new sys.stdout and uses the regular cout. On UNIX you can pipe that back to sys.stdout (wurlitzer does that) but I don’t know of any way to do that on windows. In spyder we can control the process for the kernel (if it is started from spyder) and therefore the cout can be printed in the console (spyder-ide/spyder#14783) but this is not going through the regular ipython mechanisms. That means that the cout is not sent to any other clients.

[ccordoba12]

Wurlitzer only works on Posix systems (sorry if I wasn’t clear enough about it).