I generally use many different options on maven projects to set up things like memory lower and upper limits, fail at the end, the process in batch, use x number of threads, etc. In addition to this, sometimes I need to pass flags to the JVM like add modules, garbage collector flags, etc., and it is difficult to remember and also error-prone to have something like this:

$ JAVA_OPTS="-Xms512m -Xmx1024m -Djava.awt.headless=true" \
  mvn -B -T 4 -fae -P ci verify

or even worst with the extended version of the flags:

$ JAVA_OPTS="-Xms512m -Xmx1024m -Djava.awt.headless=true" \
mvn --batch-mode --threads 4 -fail-at-end --activate-profiles ci verify

Fortunately for us, since maven 3.3.1, we now can setup this per project, including the flags in these two files relatives to the project directory:

.mvn/maven.config with:

-B -T 4 -fae -P ci

.mvn/jvm.config with:

-Xms512m -Xmx1024m -Djava.awt.headless=true

Now, all we need to do is run the maven command, and the settings in the files will be honored:

$ mvn verify