以及Bash和expect的完全自动化方式（在本例中，我们在OS和PostgreSQL运行时级别为新的PostgreSQL管理员提供新设置的PostgreQL密码）：

  # The $postgres_usr_pw and the other Bash variables MUST be defined
  # for reference the manual way of doing things automated with expect bellow
  #echo "copy-paste: $postgres_usr_pw"
  #sudo -u postgres psql -c "\password"
  # The OS password could / should be different
  sudo -u root echo "postgres:$postgres_usr_pw" | sudo chpasswd

  expect <<- EOF_EXPECT
     set timeout -1
     spawn sudo -u postgres psql -c "\\\password"
     expect "Enter new password: "
     send -- "$postgres_usr_pw\r"
     expect "Enter it again: "
     send -- "$postgres_usr_pw\r"
     expect eof
EOF_EXPECT

  cd /tmp/
  # At this point the 'postgres' executable uses the new password
  sudo -u postgres PGPASSWORD=$postgres_usr_pw psql \
    --port $postgres_db_port --host $postgres_db_host -c "
  DO \$\$DECLARE r record;
     BEGIN
        IF NOT EXISTS (
           SELECT
           FROM   pg_catalog.pg_roles
           WHERE  rolname = '"$postgres_db_useradmin"') THEN
              CREATE ROLE "$postgres_db_useradmin" WITH SUPERUSER CREATEROLE
              CREATEDB REPLICATION BYPASSRLS
 PASSWORD '"$postgres_db_useradmin_pw"' LOGIN ;
        END IF;
     END\$\$;
  ALTER ROLE "$postgres_db_useradmin" WITH SUPERUSER CREATEROLE
  CREATEDB REPLICATION BYPASSRLS
PASSWORD  '"$postgres_db_useradmin_pw"' LOGIN ;
 "

使用此项：

\password

输入该用户的新密码，然后确认。如果您不记得密码，并且想更改密码，您可以以“postgres”登录，然后使用此选项：

ALTER USER 'the username' WITH PASSWORD 'the new password';

以及Bash和expect的完全自动化方式（在本例中，我们在OS和PostgreSQL运行时级别为新的PostgreSQL管理员提供新设置的PostgreQL密码）：

  # The $postgres_usr_pw and the other Bash variables MUST be defined
  # for reference the manual way of doing things automated with expect bellow
  #echo "copy-paste: $postgres_usr_pw"
  #sudo -u postgres psql -c "\password"
  # The OS password could / should be different
  sudo -u root echo "postgres:$postgres_usr_pw" | sudo chpasswd

  expect <<- EOF_EXPECT
     set timeout -1
     spawn sudo -u postgres psql -c "\\\password"
     expect "Enter new password: "
     send -- "$postgres_usr_pw\r"
     expect "Enter it again: "
     send -- "$postgres_usr_pw\r"
     expect eof
EOF_EXPECT

  cd /tmp/
  # At this point the 'postgres' executable uses the new password
  sudo -u postgres PGPASSWORD=$postgres_usr_pw psql \
    --port $postgres_db_port --host $postgres_db_host -c "
  DO \$\$DECLARE r record;
     BEGIN
        IF NOT EXISTS (
           SELECT
           FROM   pg_catalog.pg_roles
           WHERE  rolname = '"$postgres_db_useradmin"') THEN
              CREATE ROLE "$postgres_db_useradmin" WITH SUPERUSER CREATEROLE
              CREATEDB REPLICATION BYPASSRLS
 PASSWORD '"$postgres_db_useradmin_pw"' LOGIN ;
        END IF;
     END\$\$;
  ALTER ROLE "$postgres_db_useradmin" WITH SUPERUSER CREATEROLE
  CREATEDB REPLICATION BYPASSRLS
PASSWORD  '"$postgres_db_useradmin_pw"' LOGIN ;
 "

将用户“postgres”的密码更改为“postgress”：

# ALTER USER postgres WITH ENCRYPTED PASSWORD '<NEW-PASSWORD>';

对于我在Ubuntu 14.04（Trusty Tahr）上的案例，安装了PostgreSQL 10.3：我需要遵循以下步骤

su-postgres将用户切换到postgrespsql以进入PostgreSQL shell\密码，然后输入密码Q退出shell会话然后，通过执行exit并配置pg_hba.conf（我的位于/etc/postgresql/10/main/pg_hba.coff），切换回root，确保您有以下行本地所有postgres md5通过service PostgreSQL Restart重新启动PostgreSQL服务现在切换到postgres用户并再次输入PostgreSQL shell。它将提示您输入密码。

更改密码：

 sudo -u postgres psql

Then

\password postgres

现在输入新密码并确认。

然后\q退出。