Maven: How do I activate a profile from command line?

Both commands are correct :

mvn clean install -Pdev1
mvn clean install -P dev1

The problem is most likely not profile activation, but rather the profile not accomplishing what you expect it to.

It is normal that the command :

mvn help:active-profiles

does not display the profile, because is does not contain -Pdev1. You could add it to make the profile appear, but it would be pointless because you would be testing maven itself.

What you should do is check the profile behavior by doing the following :

1. set activeByDefault to true in the profile configuration,
2. run mvn help:active-profiles (to make sure it is now always activated, even without -Pdev1),
3. run mvn install.

It should produce the same result as before, and therefore confirm that the problem is the profile not doing what you expect.