What should go to stdout/stderr and why Python logging write everything to stderr?

[Michael Torrie]

On 1/3/23 11:45, Keith Thompson wrote:
> MRAB <python at mrabarnett.plus.com> writes:
> [...]
>> The purpose of stderr is to display status messages, logging and error
>> messages, even user prompts, and not mess up the program's actual 
>> output. This is important on a *nix system where you might be piping
>> the output of one program into the input of another.
> 
> I would expect user prompts to be written to stdout, or perhaps to some
> system-specific stream like the current tty, not to stderr.  If a
> program has user prompts, it probably doesn't make sense to pipe its
> output to the input of another.

I can't think of a specific example, but I know I have piped the output
of a program while at the same time interacting with a prompt on stderr.
 A rare thing, though.

Maybe some day an interface and shell syntax will be developed to
interact with an arbitrary number of standard streams.  Current piping
syntax really only works well with one stream and even trying to use
stderr and stdout with pipes and filters in a shell is awkward.