Re: "peer" authentication: cannot make "pg_ident.conf" work as I believe that the doc says that it should

sudo systemctl stop  postgresql
sudo systemctl start postgresql
pg_ctl reload -D /etc/postgresql/11/main/

(I know that I could've used "systemctl restart ".) Like I said elsewhere, the "reload" seems to be superfluous. But it costs nothing to do it.

Then I did "su bob" and first did this sanity test:

psql -h localhost -p 5432 -d postgres -U alice

That worked fine—and "select current_role" showed "alice".

Then I did the spelling for "peer", to authorize explicitly as "bob":

psql -d postgres -U bob

That worked too so that "select current_role" now showed "bob". Finally, I omitted "bob" here in the belief that this would make my mapping kick in and authorize using the cluster role "alice":

psql -d postgres

It got me in without error. (And, as hoped for, there was no password challenge.) But "select current_role" showed that the mapping had been ignored and that I was connected again as "bob".

What am I doing wrong?