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What's wrong on using Popen's communicate method?


On Thu, 04 Jul 2019 10:36:36 +1000, Cameron Simpson wrote:

> On 03Jul2019 16:57, Jach Fong <jfong at ms4.hinet.net> wrote:
>>I have the test0.py below. I expect to see 'abcd' showing in the notepad window:
>>---------
>>import subprocess as sp
>>p0 = sp.Popen('notepad.exe', stdin=sp.PIPE)
>>p0.communicate(input=b'abcd')
>>---------
>>But nothing happens. The notepad is completely empty. What have I missed?
>>--Jach
>>
>>PS. I am using python 3.4 on Windows Vista
> 
> Well I am not a Windows person, but in most GUI environments a desktop 
> app such as Notepad does not read from its standard input - it reads 
> keyboard stuff though the GUI interface instead. So it is ignoring your 
> input data - this approach will generally fail with any desktop app on 
> any platform.
> 
> You may need to investigate generating synthetic keystrokes somehow.
> 
> Or alternatively write your data to a text file and hand the name of the 
> text file to notepad as a file to edit.
> 
> Cheers,
> Cameron Simpson <cs at cskk.id.au>

I block googlegroups so I don't see the original post.  I am
talking to the OP.

Take a look at the SendKeys module.

https://pypi.org/project/SendKeys/

-- 
<Wildman> GNU/Linux user #557453
The cow died so I don't need your bull!