When Maven executes phase or goal or lifecycle?

Question

When I was reading about Maven goals, phases on Stack Overflow, I came across two links in which one says:

when you execute maven you can specify a goal or a phase.

– What is the difference/relation between maven goals and phases?

and the other says:

You can't call the life-cycle-phase itself but you can call the goals of the plugins which are bound to the life-cycle-phases.

– Executing a specific Maven phase

Which one is right? Or am I not understanding it?

Also can some give me simple examples Maven executing lifecycle/phase/goal. And also Maven knows that it has to run phase or a goal? E.g. when I say mvn install, is it install phase or goal?

Answer 1

When you invoke a single plugin, you need to invoke a goal of that plugin. Like

mvn dependency:tree

in this case you are invoking the goal tree of the dependency plugin

On the other hand, you can invoke a phase of maven by simply doing

mvn test

In this case you are invoking not a plugin but a phase. Note that plugin goals can be bound to specific phases as well. The difference is whether you invoke the full phase (and all the preceding phases implicitly) or just a single goal of a single plugin

Here you can find all the phases of the default lifecycle (which can be modified, but i don't think you need to know about that for now), so as you can see, install is a phase