Am Montag, 10. Dezember 2007 schrieb Tom Lane:
> "Joshua D. Drake" <jd@commandprompt.com> writes:
> > As I recall there was a bug under very specific circumstances that a
> > password prompt would not appear. Thus we added the option for -W.
>
> I don't see any evidence for that theory in the CVS logs ..
> Peter seems to have invented -W out of whole cloth.
Way back when, there was no way to set the user name on the psql command line.
The only way was to use the option -u and type it in. (Well, you could set
PGUSER, but that's obviously not quite fun.) But -u also forced a password
prompt, even if you didn't need a password. So the functionality of the -u
option was split into the -U and -W options. The only difference is that -U
does not prompt, but I don't think anyone wants to argue that prompting is
better than what -U does. Note that we don't have a way to prompt for host
name, database name, etc., and shell scripting this functionality is trivial.
Way back when, psql moreover did not have the capability to automatically
recognize when a password would be required. That is, if you did not specify
one, authentication would simply fail and psql would abort. If you were
aware that a password would be required, then the only ways to supply it
would be to set PGPASSWORD (which is obviously not quite fun) or use the -u
option, which would also prompt you for a user name, even if you did not want
to specify one. So the functionality of the -u option was split into the -U
and -W options. -W does exactly half of what -u used to do.
The functionality to automatically recognize when a password would be required
and prompt was added later (or perhaps around the same time) but it was
considered a hack (it was a string comparison of the error message). It has
obviously worked out quite well anyway. I believe the documentation of
the -W option has for its entire lifetime said that it "should" normally not
be necessary.
So as far as I can tell, the available options -U and -W serve all the
existing use cases. I would have no issue with getting rid of the -W option
if someone wants to take responsibility for ensuring that it will really
never be necessary. I see no technical or usability merit in reviving the -u
option. I hope the above explanations have shed some light on that.
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
