How to check for patch conflicts before applying in Oracle

Before applying a patch, check it for conflicts against the Oracle Home. Run this from the unzipped patch directory.

# From the unzipped patch directory
cd /path/to/patch/<patch_id>
$ORACLE_HOME/OPatch/opatch prereq CheckConflictAgainstOHWithDetail -ph ./

# Also useful: check the system is ready to apply
$ORACLE_HOME/OPatch/opatch prereq CheckSystemSpace -ph ./