List all the patches that applied in oracle database

Opatch command

opatch lsinventory;

SQL Command

select * from sys.registry$history;

Automating Database Startup and Shutdown on Linux

12C

STEP 1:
Once the instance is created, edit the "/etc/oratab" file setting the restart flag for each instance to 'Y'.

ORCL:/u01/app/oracle/product/12.2.0.1/db_1:Y

STEP 2:
Create a file called "/etc/init.d/dbora" as the root user, containing the following code.
The path and instance name should be adjusted to match your installation and instance.

#!/bin/sh
# chkconfig: 345 99 10
# description: Oracle auto start-stop script.
#
# Set ORA_HOME to be equivalent to the $ORACLE_HOME
# from which you wish to execute dbstart and dbshut;
#
# Set ORA_OWNER to the user id of the owner of the 
# Oracle database in ORA_HOME.

ORA_HOME=/u01/app/oracle/product/12.2.0.1/db_1
ORA_OWNER=oracle
export ORACLE_UNQNAME=ORCL

if [ ! -f $ORA_HOME/bin/dbstart ]
then
    echo "Oracle startup: cannot start"
    exit
fi

case "$1" in
    'start')
        # Start the Oracle databases:
        # The following command assumes that the oracle login 
        # will not prompt the user for any values
        # Remove "&" if you don't want startup as a background process.
        su $ORA_OWNER -c "$ORA_HOME/bin/dbstart $ORA_HOME" &
        touch /var/lock/subsys/dbora
        ;;
    'stop')
        # Stop the Oracle databases:
        # The following command assumes that the oracle login 
        # will not prompt the user for any values
        su $ORA_OWNER -c "$ORA_HOME/bin/dbshut $ORA_HOME"
        rm -f /var/lock/subsys/dbora
        ;;
esac

STEP 3:
Use the chmod command to set the privileges to 750.

chmod 750 /etc/init.d/dbora

STEP 4:
Associate the "dbora" service with the appropriate run levels and set it to auto-start using the following command.

chkconfig --add dbora

The relevant instances should now startup/shutdown automatically at system startup/shutdown.

For other versions and more details, Please refer to the below reference URL:
https://oracle-base.com/articles/linux/automating-database-startup-and-shutdown-on-linux