[Tutor] Howto display progress as cmd is being executed via subprocess ?

[Alan Gauld]

On 13/06/16 17:50, Ramanathan Muthaiah wrote:

> Am aware of the module called 'progressbar' that can do this magic of
> displaying progress as the cmd is executed.

I'm not familiar with it, I don't believe its in the standard library?
So I can only offer generalized advice.

> def main():
>         progress = ProgressBar()
>         for num in progress(range(80)):
>                 time.sleep(0.15)

I have no idea how that works since I don;t know anything
about the progress API. Its apparently callable and takes
a sequence and returns a sequence but what it does with
those values I can't say.

> And, I have this piece of code that executes set of cmds 
> This too works without any issues until now.
> 
> try:
>                  dlog = subprocess.check_output([cmd],
> stderr=subprocess.STDOUT, shell=True)
> except subprocess.CalledProcessError, e:
>                 dlog = e.output
> 
> Question:
> 
> Am lost as to how to combine the progressbar and subprocess code snippets

Here's where the generalized help comes in.
There are two common approaches:
1) Split your work into bite sized chunks. Repeatedly call
those chunks until done and update progress after each chunk.
2) Run your work in a separate thread and in the main thread
update the progress bar either based on an estimated time
to complete or by reading the process output in some way.

How that translates to your particular ProgressBar I can't say.
But it might give you ideas. Or maybe the start of a specific
question to the module support forum/list or author

-- 
Alan G
Author of the Learn to Program web site
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