• Last tested on Oracle 18.4.0.0.0, CentOS 7.6.1810 (2019-06-21)

Shutdown the database.

$ sqlplus / as sysdba
SQL> SHUTDOWN IMMEDIATE

Start the database.

SQL> STARTUP
SQL> ALTER PLUGGABLE DATABASE ALL OPEN;

Enable automatic shutdown and startup.

$ systemctl daemon-reload
$ systemctl enable oracle-xe-18c