psql: FATAL: Ident authentication failed for user "postgres"

I encounter this problem when trying to list down the db for a newly installed Postgress on a machine ::

#host:>psql -Upostgres -l

psql: FATAL:  Ident authentication failed for user "postgres"

What to do::

1-> su - postgres    and then run psql.  Or:  Edit pg_hba.conf, and write   trust  instead of "ident sameuser" -- then reload PostgreSQL

Open up the pg_hba.conf 

# Put your actual configuration here

# ----------------------------------

#

# If you want to allow non-local connections, you need to add more

# "host" records. In that case you will also need to make PostgreSQL listen

# on a non-local interface via the listen_addresses configuration parameter,

# or via the -i or -h command line switches.

#

# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD

# "local" is for Unix domain socket connections only

local   all         all                                      trust          <-- default is ident sameuser

# IPv4 local connections:

host    all         all         127.0.0.1/32          trust         <-- default is ident sameuser

# IPv6 local connections:

host    all         all         ::1/128                  trust         <-- default is ident sameuser