lsnrctl: command not found in Ubuntu 18.04

I am trying to make connection to Oracle Database 18c XE with sqldeveloper,

but I am getting :

Status : Failure -Test failed: Listener refused the connection with the following error:ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

So I am trying to start my listener, which I have inside/opt/oracle/product/18c/dbhomeXE/network/admin/samples

And I am getting lsnrctl: command not found

I am also getting the same message for sqlplus which is inside /opt/oracle/product/18c/dbhomeXE/bin

I know that you are going to say Oracle is not supported for Ubuntu,

but I am really only capable of using Ubuntu..

[CLOSED] I successfully was able to connect to oracle database via sqldeveloper 17.3 by following this link steps and guide:

http://meandmyubuntulinux.blogspot.com/2012/06/trouble-shooting-oracle-11g.html