Spring Shell 3
Spring Shell 3 is a work to solely depend on Spring Boot 2.x and not trying to keep any backward compatibility with older Spring Shell 1.x nor Spring Boot 1.x.
The project comes with a sample application, showcasing the various ways you can write commands.
./mvnw install ./mvnw -pl spring-shell-samples spring-boot:run
From there, try typing
help <commmand> at the shell prompt.