A Better RVM Bash Prompt

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Not knowing where you are while using RVM can be a frustrating experience. Which version of ruby am I using? Which gemset? And using per-project .rvmrc files, while super-cool, makes the situation even worse.

RVM ships with the rvm-prompt script, which you can use in your $PS1 setup, but it neglects gemsets, and doesn't skip default values.

Problem, meet Solution.

So, here's a new bash prompt function that prints the RVM ruby version and gemset, but only if they're different from the defaults.

function __git_dirty {
  git diff --quiet HEAD &>/dev/null 
  [ $? == 1 ] && echo "!"

function __git_branch {
  __git_ps1 " %s"

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 $2}')
  [ "$version" == "1.8.7" ] && version=""
  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="$B\$(__my_rvm_ruby_version)$Y\h$W:$EMY\w$EMW\$(__git_branch)$EMY\$(__git_dirty)${NONE} $ "

unset bash_prompt

And here's the result (minus my color codes):

tardis:~ $ rvm 1.9.1
1.9.1 tardis:~ $ rvm gemset use rail3
Now using gemset 'rail3'
1.9.1%rail3 tardis:~ $ rvm  default
tardis:~ $ 

Update: Looks like I was a version behind on RVM, but the new rvm-prompt still doesn't handle defaults. I've also updated the code to account for the change from % to @.

Feel free to submit corrections via github