rvm: how do I really know it works - jruby

Question

I installed rvm successfully and then installed ruby 1.8.7, ruby 1.9.2, and jruby 1.6.0. I currently use 1.8.7 for all of my rails projects, but I would like to experiment with 1.9.2, and I would also like to deploy jruby on those environments which are Java-specific.
So, I used rvm to select jruby and then I ran my current rails app on mongrel # localhost:3000. It worked great. Then, I ran a Linux process command and looked at the names of the processes running and I found ruby1.8. Does that mean that the Mongrel instance loaded ruby 1.8, but rails is using jruby-1.6.0? I don't know. Who can tell me how to determine that I really am running jruby?

Answer 1

type rvm | head -1
The above line should say that RVM is a function and confirms it was installed correctly.
Did you have trouble with instructions on entering the line
[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # This loads RVM into a shell session.
into your bash profile? That was a little unclear in my opinion. If it's that, you need to go to your home directory and make a .bash_profile (source: http://donovan.covblogs.com/archives/027838.html)
The above needs to be done before you can rly ensure ruby 1.9.2 is installed, else it'll be forgotten/lost once you close your shell.
Regarding the version of ruby you're using, make sure you're setting the default version. Below was taken from the Ruby on Rails 3 tutorial so feel free to change some naming conventions:
$ rvm --create 1.8.7-p174#rails2tutorial
$ rvm --create use 1.9.2#rails3tutorial
then
$ rvm --default use 1.9.2#rails3tutorial
Finall, type $ ruby -v and you should get ruby 1.9.2
Source: http://ruby.railstutorial.org/chapters/beginning#sec:install_ruby

Answer 2

I found this very helpful after starting to use rvm: i added this to the end of my .bashrc file: it puts the currently selected rvm and gemset at the start of the command prompt, in red: most of the following script is taken up with defining colors - you could delete the ones you don't need once you choose the colors you want.
##################################################
### RVM-specific command line (PS1): show current rvm and gemset
function __my_rvm_ruby_version {
local gemset=$(echo $GEM_HOME | awk -F'#' '{print $2}')
[ "$gemset" != "" ] && gemset="#$gemset"
local version=$(echo $MY_RUBY_HOME | awk -F'-' '{print $2}')
local full="$version$gemset"
[ "$full" != "" ] && echo "$full "
}
bash_prompt() {
local NONE="\[\033[0m\]" # unsets color to term's fg color
# regular colors
local K="\[\033[0;30m\]" # black
local R="\[\033[0;31m\]" # red
local G="\[\033[0;32m\]" # green
local Y="\[\033[0;33m\]" # yellow
local B="\[\033[0;34m\]" # blue
local M="\[\033[0;35m\]" # magenta
local C="\[\033[0;36m\]" # cyan
local W="\[\033[0;37m\]" # white
# emphasized (bolded) colors
local EMK="\[\033[1;30m\]"
local EMR="\[\033[1;31m\]"
local EMG="\[\033[1;32m\]"
local EMY="\[\033[1;33m\]"
local EMB="\[\033[1;34m\]"
local EMM="\[\033[1;35m\]"
local EMC="\[\033[1;36m\]"
local EMW="\[\033[1;37m\]"
# background colors
local BGK="\[\033[40m\]"
local BGR="\[\033[41m\]"
local BGG="\[\033[42m\]"
local BGY="\[\033[43m\]"
local BGB="\[\033[44m\]"
local BGM="\[\033[45m\]"
local BGC="\[\033[46m\]"
local BGW="\[\033[47m\]"
local UC=$W # user's color
[ $UID -eq "0" ] && UC=$R # root's color
PS1="$R\$(__my_rvm_ruby_version)$Y\h$W:$EMY\W${NONE}$ "
}
bash_prompt
unset bash_prompt
############## PS1 editing section ends