这就是我想要做的：
echo "local all all trust" >> /etc/postgresql/9.5/main/pg_hba.conf
systemctl restart postgresql
pgbench -i
然后我得到：
connection to database "" failed:
FATAL: role "root" does not exist
如果我尝试使用现有用户：
pgbench -i -U postgres
connection to database "postgres" failed:
FATAL: Peer authentication failed for user "postgres"