Love GVM for switching between Grails versions. However my install in Ubuntu stopped working a few weeks ago and I've been puzzled ever since. If you run gvm, and it stops working where the command 'gvm' returns nothing, run this:
then you can do 'gvm selfupdate' to bring it up to date. Working like a champ now!
If you do Groovy/Grails/Griffon/Gradle/Vertx development and don't use GVM you should.
Check it out at http://gvmtool.net/