Problem with postgresql configuration on Fedora 18

[Roger]

I am hoping someone can talk me through a postgresql problem on my 
Fedora 18 box.
Have a Rails 4 app working with sqlite and mysql but need to have it in 
postgres so that I can use it with Heroku.
Had postgres working in Fedora 16 several months ago for my first Heroku 
test application.

Am now using Fedora 18 for everything but having a problem with apache 
mysteriously failing with Drupal,(written about some weeks ago) so am 
moving to Ruby 2 and Rails 4 which uses WEBrick on dev and test.

Has latest Fedora 18  updates, (PostgreSQL) 9.2.4 is installed and 
accessible.
Sudo -u postgres psql  accesses postgres  \du shows users:  admin, 
postgres and home_user.

In a user terminal  I enter psql and get psql: FATAL:  role "Home_user" 
does not exist. psql -Uadmin gives: psql: FATAL:  Peer authentication 
failed for user "admin".  psql postgres gives:psql: FATAL:  role 
"Home_user" does not exist

Why is psql attempting login as my Fedora username?

There's also a strange error when I successfully log in as sudo -u 
postgres psql: - could not change directory to "/home/Home_user"l.

As root, my experimental /var/lib/pgsql/data/pg_hba.conf contains:
# TYPE  DATABASE        USER            ADDRESS METHOD
# "local" is for Unix domain socket connections only
local   all             all trust
# IPv4 local connections:
host    all             all             127.0.0.1/32 trust
# IPv6 local connections:
host    all             all             ::1/128 trust
# Allow replication connections from localhost, by a user with the 
replication privilege.
local   all             127.0.0.1/32 trust
#host    replication     postgres        127.0.0.1/32            md5
#host    replication     postgres        ::1/128                md5

sudo systemctl start postgresql.service gives no notice that it has 
started psql
ps aux |grep psql shows Home_user   5734  0.0  0.0 109180   872 pts/0    
S+   21:10   0:00 grep --color=auto psql it seems to be finding the 
fedors user login.

I have tried peer, trust, ident and md5.
I see there is #host    replication     @default_username@ 
127.0.0.1/32    @authmethodhost@ in the /usr/share/pgsql/pg_hba.conf. I 
don't know whether psql uses both this and the above pg_hba.conf. Have 
tried switching off one then the other and having both onn but psql 
still fails.
I do not know which configuration makes it seek the default Fedora 
username as a login.


ps aux |grep postgres shows:
postgres  1378  0.0  0.3 224528  7540 ?        S    17:29   0:00 
/usr/bin/postgres -D /var/lib/pgsql/data -p 5432
postgres  1492  0.0  0.0 190808   948 ?        Ss   17:29   0:00 
postgres: logger process
postgres  1570  0.0  0.0 224628  1808 ?        Ss   17:29   0:00 
postgres: checkpointer process
postgres  1571  0.0  0.0 224528  1328 ?        Ss   17:29   0:00 
postgres: writer process
postgres  1572  0.0  0.0 224528  1096 ?        Ss   17:29   0:00 
postgres: wal writer process
postgres  1573  0.0  0.1 225348  2404 ?        Ss   17:29   0:00 
postgres: autovacuum launcher process
postgres  1574  0.0  0.0 193036  1216 ?        Ss   17:29   0:00 
postgres: stats collector process
Home_user   5756  0.0  0.0 109184   880 pts/0    S+   21:12   0:00 grep 
--color=auto postgres

So it seems postgres is started but why the last line shows Home_user 
I'm at a loss to understand.
I have rebooted, restarted apache and postgres and now have no clue 
where to look next.
I am wondering whether the possible fault I am experiencing in apache 
may be causing the postgres problem because of the browser on 127.0.0.1.
I have no problem browsing the web and watching tuts on RoR24
Very puzzling and I'd love to understand what it is that I'm not seeing 
and how the problem can be fixed.

Thank you in advance
Roger