Enable auto-start on boot:
Then:
If you prefer sqlplus not installed yet, install Oracle Instant Client separately, or use the SQL*Plus included in the XE installation: install oracle xe 21c on ubuntu
sqlplus system@localhost:1521/XE Enter the password you set during configuration. Enable auto-start on boot: Then: If you prefer
sudo systemctl enable oracle-xe-21c Connect as SYSTEM : install Oracle Instant Client separately