spring-boot default log location

Question

In a spring-boot application I can specify a custom log file with

java -jar spring-boot-app.jar --logging.file=/home/ubuntu/spring-boot-app.log

But if I don't specify one, where do they go?

I couldn't find it in any of the following folders:

/tmp/
/var/log/
~/

I do not have spring-boot-starter-logging or any extra log dependencies.

I was hoping to have something similar to catalina.out since the default configuration runs an embedded Tomcat:

INFO 10374 --- [main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8100 (http)

Answer 1

Spring Boot uses Commons Logging for all internal logging, but leaves the underlying log implementation open.

Default configurations are provided for Java Util Logging, Log4J, Log4J2 and Logback. In each case loggers are pre-configured to use console output with optional file output also available.

From the Spring Boot logging documentation.

The default log configuration will echo messages to the console as they are written. So until you explicitly specify a file as you described, it stays in the Console.