Gum automatically detects if the project is Gradle or Maven based and runs the appropriate command. However in the case that Gum guesses wrong you can force a specific build tool to be used.
Gum supports the following flags
-gc displays current configuration and quits
-gd displays debug information
-gg force Gradle build
-gh displays help information
-gj force jbang execution
-gm force Maven build
-gn executes nearest build file
-gq run gm in quiet mode
-gr do not replace goals/tasks
-gv displays version information
Gum will execute the build based on the root build file unless -gn is specified, in which case the nearest build file will be selected. If a specific build file is given (-b, --build-file for Gradle; -f, --file for Maven) then that file will be used instead.