Apply Oracle patch

1. Shutdown Oracle instance
Login with oracle user, type the command:
$dbstop $ORACLE_HOME

2. Download patches, go to https://support.oracle.com then search patch name/number. Upload patches (ex: 16902043, 17762528) to server (ex: /home/oracle) and extract.

3. Download Oracle opatch tool (ex: 68806880)

4. Copy OPatch folder in $ORACLE_HOME to another backup place

$cp $ORACLE_HOME/OPatch /backup
$ rm -r $ORACLE_HOME/OPatch/*

 5. Copy opatch to $ORACLE_HOME

$cp p68806880....zip $ORACLE_HOME
$cd $ORACLE_HOME
$ unzip p68806880....zip

6. Apply patch

$cd 16902043
$$ORACLE_HOME/OPatch/opatch apply
$cd 17762528
$$ORACLE_HOME/OPatch/opatch apply

7. Start oracle database

$dbstart $ORACLE_HOME