How to check database startup and shutdown details in Alertlog

How to check database startup and shutdown details in Alertlog

Db startup time:

cat alert*log |awk 'BEGIN{buf=""} /[0-9]:[0-9][0-9]:[0-9]/{buf=$0} /Starting ORACLE/{print buf,$0}'

Db shutdown time:

cat alert*log |awk 'BEGIN{buf=""} /[0-9]:[0-9][0-9]:[0-9]/{buf=$0} /Shutting down instance/{print buf,$0}'