[Tutor] subprocess figuring out what is in stdout

[Nathan Smith]

I'm working with a program which requires interactive shell like reading 
of the output, EG user types input in response to various outputs 
displayed to them.

Unfortunately, in some cases, the program being run is not either 
printing an "\n" at the end of particular lines, or is not flushing  it.

This only happens with specific points and is easily responsed. 
Unfortunately, the unflushed data does not appear until the question 
being asked is answered (rather unhelpful to the user)


My current implementation uses readline which is why I suspect the 
problem may be that there is no "\n" character at the end, hence why 
readline is not flushing it until more output is added.


One possible solution I found is to do stdout.read(1) and do it 
character by character, but the efficiency seems low and this also 
presents some other problems with other parts of my program.


To that end I was wondering, perhaps is there a way to tell how many 
characters/bytes are in a stdout buffer before it is read? That way 
read(x) could give the exact number.


I've seen some references talk about a way of making non blocking ports, 
but these seem to be linux solutions and don't play nice with windows so 
this doesn't really seem to be an option.



thanks in advance for any tips.


-- 

Best Wishes,

Nathan Smith, BSC


My Website: https://nathantech.net