Running a command line program and reading the result as it runs

[Ian Simcock]

Chris Angelico wrote:
> Is the program actually producing output progressively? I just tried
> your exact code with "dir /ad /s /b" and it worked fine, producing
> output while the dir was still spinning (obviously setting shell=True
> to make that work, but I don't think that'll make a difference). It
> may be that pip buffers its output. Is there a parameter to pip to
> make it pipe-compatible?
>
> ChrisA
>

If I run pip in the command window I can see it's output appearing line 
by line rather than on one block.

I tried the code with the dir command but it's too fast for me to be 
sure if it's working or not.

I tried again using the command "ping google.com" instead since I know 
that output's slowly and it something that everyone should have. In the 
command window I can see that the output appears over time, but from 
python I get nothing for a while and then suddenly get all the output in 
one rapid go.

Can you think of anything else I can look at?

Ian Simcock.