rvm, z and nave automated

rvm_z_nave_automated.sh

rename_function() {
    declare -F $1 > /dev/null || return 1
    eval "$(echo "${2}()"; declare -f ${1} | tail -n +2)"
}

if [[ $(type -t old_cd) == "function" ]]; then
  echo "old_cd already exists" > /dev/null
elif [[ $(type -t cd) == "function" ]]; then
  rename_function cd old_cd
  cd() {
    old_cd "$*"
    exec nave auto
  }
  if [[ $(type -t z) == "alias" && $(type -t old_z) != "alias" ]]; then
    unalias z
    function z { 
      _z 2>& "$*"
      exec nave auto
    }   
  fi
else
  alias cd='exec nave auto'
fi