Maven: specify the outputDirectory only for packaging a jar?

Question

How can I specify the outputDirectory only for packaging a jar?

http://maven.apache.org/plugins/maven-jar-plugin/jar-mojo.html this shows all parameters, but how can

Answer 1

on command line

-DoutputDirectory=

and in pom.xml

  
    
      org.apache.maven.plugins
      maven-jar-plugin
      2.3.1
      
        /my/path