The DHIS2 application log output is directed to multiple files and locations. First, log output is sent to standard output. The Tomcat servlet container usually outputs standard output to a file under "logs":
Second, log output is written to a "logs" directory under the DHIS2 home directory as defined by the the DHIS2_HOME environment variables. There is a main log file for all output, and separate log files for various background processes. The main file includes the background process logs as well. The log files are capped at 50 Mb and log content is continuously appended.
<DHIS2_HOME>/logs/dhis.log <DHIS2_HOME>/logs/dhis-analytics-table.log <DHIS2_HOME>/logs/dhis-data-exchange.log <DHIS2_HOME>/logs/dhis-data-sync.log
In order to override the default logging you can specify a Java system property with the name log4j.configuration and a value pointing to the Log4j configuration file on the classpath. If you want to point to a file on the file system (i.e. outside Tomcat) you can use the file prefix e.g. like this:
Java system properties can be set e.g. through the JAVA_OPTS environment variable.
DHIS2 will eventually phase out logging to standard out / catalina.out and as a result it is recommended to rely on the logs under DHIS2_HOME.