R12.2 Apache and Weblogic log locations:

Apache Logs

cd $IAS_ORACLE_HOME/instances/*/diagnostics/logs/OHS/EBS_web_*/

OPMN Log

cd $IAS_ORACLE_HOME/instances/*/diagnostics/logs/OPMN/opmn/

Weblogic Logs

cd $IAS_ORACLE_HOME/../wlserver_10.3/common/nodemanager $EBS_DOMAIN_HOME/servers/oa*/logs/

 $EBS_DOMAIN_HOME/servers/forms*/logs/
 $EBS_DOMAIN_HOME/servers/AdminServer/logs/
 $EBS_DOMAIN_HOME/sysman/log/