psql: FATAL: Peer authentication failed for user "xnat01"

jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ sudo vi /etc/postgresql/9.4/main/pg_hba.conf
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ sudo -i -u postgres
postgres@klein:~$ psql
psql (9.4.8)
Type "help" for help.$ sudo vi /etc/postgresql/9.4/main/pg_hba.conf

postgres=# SELECT pg_reload_conf();
postgres-# \q
postgres@klein:~$ exit
logout
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ psql -d xnat -f sql/xnat.sql -U xnat01
psql: FATAL:  Peer authentication failed for user "xnat01"
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$  sudo -iu postgres psql -c "SELECT pg_reload_conf();"
 pg_reload_conf
----------------
 t
(1 row)

jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ psql -d xnat -f sql/xnat.sql -U xnat01
psql: FATAL:  Peer authentication failed for user "xnat01"



I have these in pg_hba.conf:

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

local   xnat            xnat01          localhost               trust


jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ vi /etc/postgresql/9.4/main/pg_hba.conf
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ sudo vi /etc/postgresql/9.4/main/pg_hba.conf
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ sudo -i -u postgres
postgres@klein:~$ psql
psql (9.4.8)
Type "help" for help.

postgres=# SELECT pg_reload_conf();
 pg_reload_conf
----------------
 t
(1 row)

postgres=# \q
postgres@klein:~$ exit
logout
jalal@klein:~/computer_vision/XNAT/xnat/deployments/xnat/sql$ psql -d xnat -f sql/xnat.sql -U xnat01
psql: FATAL:  Peer authentication failed for user "xnat01"