[m2] --reactor command line switch

[David Jackman <Da...@fastsearch.com>]

I would like to execute a goal like scm:update for all the projects in
my multiproject pom.  It seems like the --reactor switch on mvn command
line should do this, but it doesn't ("Cannot execute mojo: update. It
requires a project with an existing pom.xml, but the build is not using
one.").  
 
Am I understanding the switch correctly?  Are the command line switches
documented anywhere?  Is there a right way to do what I'm trying to do?
 
..David..