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Date: Wed, 06 May 2015 20:58:13 -0400
From: Dave Angel <davea@davea.name>
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Subject: Re: PEP idea: On Windows, subprocess should implicitly support .bat and .cmd scripts by using FindExecutable from win32 API
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On 05/06/2015 06:11 PM, Stefan Zimmermann wrote:
> Hi.
>
> I don't like that subprocess.Popen(['command']) only works on Windows if there is a command.exe in %PATH%.

  As a Windows user you would normally expect that also command.bat and 
command.cmd can be run that way.
>

and command.com.

If it's really unfortunate that you picked "command" for your sample 
program name.  Since command.com was the shell in MSDOS, I was about to 
point you to COMSPEC to address your problem.

There's nothing Windows-specific about that behaviour.  In Linux, there 
are bash commands that can only be run by using shell=True.  Fortunately 
Popen didn't make the mistake of pretending it's a shell.

There is lots more to running a batch file than launching it.  The whole 
syntax of the rest of the commandline differs when you're doing that.

> There are simple workarounds like Popen(..., shell=True) but that is a heavy overhead for .exe files.

And the reason there's such an overhead is because you're requesting the 
services of the shell.  If you don't need those services, use shell=False.

>
> Currently I use pywin32 and call Popen([win32api.FindExecutable('command')[1]]) as a workaround. This has zero overhead.
>
> It should be default for Popen to call FindExecutable internally.
>
> Was this discussed before?
> Is it worth a PEP?
> Or at least an issue?
>
> Cheers,
> Stefan
>


-- 
DaveA