How will you check whether database active or not from OS

There are so many options to check whether DB is active or not1. ps -ef |grep ora2. ps -ef |grep ora_3. ps -ef |grep pmon4. R3trans -d ; give RC - 0000 means active other than 0000 is error5. in Brtools 1.Instance Management, 6 - Show instance status, 3-Database instance, give the instance name i mean Database Name and press continue....give the status s6. we can also check for SQLSQL> select status from v$instance;STATUS------------OPEN7. From SAPDBA, it will show the status on top.