Where does tomcat put the System.out.println output ?
I'm not interested in out.println. I'm using a system that uses system.out to log issues, like login success/fail, and I need to look to that generated "log".
It usually prints to catalina.out.
It is highly unrecommended to log using system.out.println() from several reasons:
- you cannot control which messages are logged and which aren't unless you change the code
- catalina.out just grow all the time, and you cannot move it so that tomcat will create another one.
A better solution is to use one of the popular (and mature) logging frameworks:
- java.util.logging (actually used by tomcat itself and you have no third party dependencies)
- Log4j
- Logback
A good solution which is backed by log4j, is to use Jakarta's log tag library, where you can have your logging messages in any of this forms
<log:info message="this is a message"/>
<log:info category="foo.bar" message="this is a message"/>
<log:info category="foo.bar">
this is a message
</log:info>
CATALINA_HOME/logs/stdout_YYYYMMDD.log
is the default, where CATALINA_HOME is your base Tomcat directory. There are various ways to change this programatically and via configuration.
来源：https://stackoverflow.com/questions/1543997/where-does-system-out-println-print-from-a-jsp