[Python-Dev] subprocess not escaping "^" on Windows

[Guido van Rossum]

On Sun, Jan 7, 2018 at 12:30 PM, Gregory P. Smith <greg at krypto.org> wrote:

> the best way to improve shell escaping on windows is to send a PR against
> the list2cmdline code that escapes everything you believe it should when
> running on windows. With hyperlinks to the relevant msdn info about what
> might need escaping.
>

Agreed. FWIW the call to list2cmdline seems to compound the problem, since
it just takes args and puts double quotes around it, mostly undoing the
work of list2cmdline. For example if I use (args=['a', 'b c'], shell=True)
I think list2cmdline turns that to args='a "b c"', and then the format()
expression constructs the command:

    cmd.exe /c "a "b c""

I really have no idea what that means on Windows (and no quick access to a
Windows box to try it) but on Windows that would create *two* arguments,
the first one being 'a b' and the second one 'c'.

At this point I can understand that Christian recommends against shell=True
-- it's totally messed up! But the fix should really be to fix this, not
inventing a new feature.

-- 
--Guido van Rossum (python.org/~guido)
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