This is a very straight forward process to start and stop Oracle Grid Control processes and the database.
To Stop Oracle Grid Control:
$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 sysdbashutdown immediate
EOF1
$ORACLE_HOME/bin/lsnrctl stop
To Start Oracle Grid Control:
$ORACLE_HOME/bin/lsnrctl start
sleep 15$ORACLE_HOME/bin/sqlplus /nolog <<EOF1
connect / as sysdbastartup
EOF1
sleep 15
$OMA_HOME/bin/emctl start agent
$OMS_HOME/bin/emctl start oms
$OMS_HOME/opmn/bin/opmnctl startall