[Python-Dev] "Deprecation" of os.system in favor of subprocess?

[Wes Turner]

Sarge is one way to appropriately wrap Process Control (with shell-like
piping of stdin and stdout between multiple processes).

os.system just calls C system(), AFAIU

subprocess.call calls subprocess.Popen, which does far more than just
wrapping C system(); though the return value is also the process returncode.


https://sarge.readthedocs.io/en/latest/

https://docs.python.org/3/library/os.html#os.system
https://github.com/python/cpython/blob/master/Modules/posixmodule.c

https://docs.python.org/3/library/subprocess.html#subprocess.Popen.returncode

https://docs.python.org/3/library/subprocess.html#subprocess.call

https://docs.python.org/3/library/subprocess.html#subprocess.check_call

https://en.wikipedia.org/wiki/System_call
https://en.wikipedia.org/wiki/Exec_(system_call)

...

"ENH: Add call, check_call, check_output, CalledProcessError,
expect_returncode"
https://bitbucket.org/vinay.sajip/sarge/pull-requests/1/enh-add-call-check_call-check_output/diff

On Wednesday, October 24, 2018, Steve Dower <steve.dower at python.org> wrote:

> On 24Oct2018 0934, Calvin Spealman wrote:
>
>> In the spirit of "There should be one-- and preferably only one --obvious
>> way to do it." this makes perfect sense.
>>
>
> To do what? There is one obvious way to run a system command, and one
> obvious way to manage subprocesses. There are also many non-obvious ways to
> run system commands, and many non-obvious ways to manage subprocesses.
>
> The distinction between "your own machine and other peoples machines" is
>> not always clear, nor planned for, nor understood by developers to be an
>> important distinction to make up-front. So the encouragement should be
>> clear.
>>
>
> Agreed. One good heuristic is whether you're putting the system command in
> a function or not, since functions are explicitly designing for reuse while
> just using it in a script is not.
>
> Simply put, there is no valid use case for os.system over subprocess by
>> remaining it must be considered redundant.
>>
>
> You have not shown this. Posting quotes followed by an unrelated
> conclusion isn't a very compelling form of argument :)
>
> Cheers,
> Steve
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