Where does System.out.print() output go in OAS?

Just to be clear, you are not supposed to use SOP. Use logging instead. Commons logging, java.util.logging, log4j, slf4j, you name it. However, what if third-party code has SOP and you wonder where the output goes when deployed in OAS (Oracle Application Server).

OAS actually dumps the output to opmn log under OAS. In my local installation, it is C:\product\10.1.3.1\OracleAS_1\opmn\logs\default_group~home~default_group~1.log. Just be aware it saves almost all output so the file could be huge.