Success with subprocess communicate on Windows?

Terry Reedy tjreedy at
Thu Jul 3 01:14:13 CEST 2014

On 7/2/2014 1:37 PM, Wolfgang Maier wrote:
> On 02.07.2014 19:31, Wolfgang Maier wrote:
>> I am not 100% sure whether that is the problem, but from what I gather
>> from the subprocess module docs the args string is passed to the Windows
>> CreateProcess function as a single string.
>> To me this seems to imply that it is passed as the lpCommandLine
>> parameter (with Null for the lpApplicationName parameter).
>> This is what Microsoft says about this case
>> (
>> <quote>
>> If lpApplicationName is NULL, the first white space–delimited token of
>> the command line specifies the module name. If you are using a long file
>> name that contains a space, use quoted strings to indicate where the
>> file name ends and the arguments begin (see the explanation for the
>> lpApplicationName parameter). If the file name does not contain an
>> extension, .exe is appended. Therefore, if the file name extension is
>> .com, this parameter must include the .com extension. If the file name
>> ends in a period (.) with no extension, or if the file name contains a
>> path, .exe is not appended. If the file name does not contain a
>> directory path, the system searches for the executable file in the
>> following sequence.
>> </quote>
>> So in your case the default behavior would be to add an .exe extension
>> to pyflakes, which is probably not what you intended ?
>> Best,
>> Wolfgang
> Ah, I forgot about your pyflakes -h example, which works, so my
> explanation must be wrong.

I appreciate the attempt. I hope there is someone who has been 
successful who can answer ;-).

Terry Jan Reedy

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