R12.2 Apache and Weblogic log file locations

Apache Logs

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

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

Weblogic Logs

$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/*

Source: Oracle® E-Business Suite
Maintenance Guide
Release 12.2