I have been using Grails a bit recently (may be the subject of a Blog entry later). There is often the need dive out to the command line to run stuff like: 

prompt% grails create-domain-class book

This has coincided with wanting to learn more about the auto complete feature of bash. I found this tip from Doyle of DoyleCentral.com but, to me, it is deficient in that it has a hard coded list of Grails targets. So, I decided to spin my own that gets the list of targets from Grails. Here is what I put into my .bashrc file: 

# Setup completion for grails. Lazy load the words and do it once only.
_grails()
{
  local cur prev
  COMPREPLY=()
  cur="${COMP_WORDS[COMP_CWORD]}"
  prev="${COMP_WORDS[COMP_CWORD-1]}"

  if [ -z "${GRAILS_TARGETS}" ]; then

    GRAILS_TARGETS=$(for i in `grails help | grep '^grails ' | sed 's/^grails *//'`; do echo -n "$i "; done)
  fi

  COMPREPLY=( $(compgen -W "${GRAILS_TARGETS}" -- ${cur}) )
}
complete -F _grails grails

This approach uses the variable GRAILS\_TARGETS to contain the list of Grails targets. It is lazily evaluated as it is expensive to calculate. Now of course you may still prefer the other approach.

PS: I am back to using Emacs Muse for writing Blog entries.