psql: FATAL: Peer authentication failed for user "expman" - postgresql

Question

I'm trying to restore a database from backup but I can't connect to postgresql.
namespace :db do
task import: :environment do
import_path = "~/backups"
sql_file = "PostgreSQL.sql"
database_config = Rails.configuration.database_configuration[Rails.env]
system "psql --username=#{database_config['username']} -no-password # {database_config['database']} < #{import_path}/#{sql_file}"
end
end
I tried changing the pg_hba.conf file (peer to md5).
In the console I tried the same thing with the super user postgres, but it still fails.
BTW, does anyone know a better way to restore a database? I used the backup gem.
EDIT:
I restarted the postgresql server and the passed the authentication. But, didn't restored the db. I reverted the changes in the file and just added -h localhost to the psql command. The database restores now. The only errors I get now are:
must be owner of extension plpgsql //and
no privileges could be revoked for "public"

Answer 1

after change pg_hba.conf, you shold reload or send a SIGHUP signal to postmaster pid. so that change applyed.
why not use psql -f to execute the backup sql file?
or you can use pg_dump backup and pg_restore restore. or copy command backup and restore.
LIKE :
digoal=# copy tbl_join_1 to '/home/pg93/tbl_join_1.dmp';
COPY 10
digoal=# delete from tbl_join_1;
DELETE 10
digoal=# copy tbl_join_1 from '/home/pg93/tbl_join_1.dmp';
COPY 10
OR
pg93#db-172-16-3-150-> pg_dump -f ./tbl_join_1.dmp -t tbl_join_1
pg93#db-172-16-3-150-> psql
psql (9.3.3)
Type "help" for help.
digoal=# drop table tbl_join_1;
DROP TABLE
digoal=# \q
pg93#db-172-16-3-150-> psql -f ./tbl_join_1.dmp
SET
SET
SET
SET
SET
SET
SET
SET
SET
CREATE TABLE
ALTER TABLE
ALTER TABLE