psql's default database on connect (our internal ref. SRP-30861)

Hello,

testpos(at)srap53dxr1:~> psql --help
...
-d, --dbname=DBNAME database name to connect to (default: "testpos")

testpos(at)srap53dxr1:~> whoami
testpos

testpos(at)srap53dxr1:~> env | grep PG
PGPASSWORD=xxxxxxxx
PGHOST=localhost
PGPORT=5432

testpos(at)srap53dxr1:~> LANG=C psql -Usisis
psql (13.3)
Type "help" for help.

sisis=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
postgres | postgres | UTF8 | de_DE.UTF-8 | de_DE.UTF-8 |
sisis | sisis | UTF8 | de_DE.UTF-8 | de_DE.UTF-8 |
...

Why psql connects to the database 'sisis'? I was expecting that it
will try to connect to a database 'testpos' as this is the UNIX login
and as '-d....' was not specified. I was expecting in this case an
error like this:

testpos(at)srap53dxr1:~> export PGDATABASE=testpos
testpos(at)srap53dxr1:~> psql -Usisis
psql: error: FATAL: database »testpos« does not exist

What do I uderstand wrong?

matthias
--
Matthias Apitz, ✉ guru(at)unixarea(dot)de, http://www.unixarea.de/ +49-176-38902045
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