I followed the steps of this document: https://docs.oracle.com/cd/E17781_01/install.112/e18802/toc.htm#XEINL121, but sqlplus doesn't start. Even if I used the command: "sqlplus /nolog". The other services start: APEX, Main page on: 127.0.0.1:8080, and It can connect with SYSTEM user in the page. However, sqlplus still doesn't start. I executed the command: /etc/init.d/oracle-xe start, and shows a message with "OK".
When I check the status of the oracle-xe service, it shows: active (exited).
What does it mean "exited"? Why not "running"?
How can I execute sqlplus?