Starting GC (as oracle software owner):
$OMA_HOME/bin/emctl start agent
$OMS_HOME/bin/emctl start oms
$OMS_HOME/opmn/bin/opmnctl startall
.. and stopping:
$OMS_HOME/opmn/bin/opmnctl stopall
$OMA_HOME/bin/emctl stop agent
$OMS_HOME/bin/emctl stop oms$ORACLE_HOME/bin/sqlplus /nolog <<EOF1
connect / as sysdba
shutdown immediate
EOF1