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

[Chris Angelico]

On Wed, 4 Jan 2023 at 09:52, Grant Edwards <grant.b.edwards at gmail.com> wrote:
>
> On 2023-01-03, Michael Torrie <torriem at gmail.com> wrote:
> > 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.
>
> Programs that ask for passwords often do it by reading/writing to fd 0
> or /dev/tty so that stdout is unaffected.
>

Reading/writing the FD is the same as using stdout (technically you'd
write to fd 1 and read from fd 0), but yes, can use /dev/tty to reach
for the console directly.

ChrisA