Starting Oracle 12c in Linux...

From terminal: oraenv
ORACLE_SID = iqora
ORACLE_HOME = /u01/app/oracle/product/12.1.0.2/iqms

From terminal: lsnrctl start

Form terminal: sqlplus / as sysdba
sql> startup;
sql>select instance_name,status,database_status from v$instance;
sql> alter system register;
sql>exit;

lsnrctl status