Set the bash prompt according to the current ruby version, node version and branch/status of the current git repository.

.ruby_node_git_prompt

#!/bin/bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the branch/status of the current git repository
#    * the return value of the previous command
#
# USAGE:
#
#   1. Save this file as ~/.git_bash_prompt
#   2. Add the following line to the end of your ~/.bashrc:
#
# if [ -f ~/.ruby_node_git_prompt ]; then
#     . ~/.ruby_node_git_prompt
# fi

#
# AUTHOR:
#
#   Scott Woods <scott@westarete.com>
#   West Arete Computing
#
#
#   Based on work by halbtuerke and lakiolen.
#
#   http://gist.github.com/31967
#
# Edited by:
#   Carlos Torrealba <catorrealbas@gmail.com>
#   for git version 2.20.1
#
# Based on work by Igor Hlina
#
# https://coderwall.com/p/qywblg

# The various escape codes that we can use to color our prompt.
        RED="\[\033[0;31m\]"
      GREEN="\[\033[0;32m\]"
     YELLOW="\[\033[0;33m\]"
       BLUE="\[\033[0;34m\]"
       CYAN="\[\033[0;35m\]"
    MAGENTA="\[\033[0;36m\]"
 LIGHT_GRAY="\[\033[0;37m\]"
  LIGHT_RED="\[\033[0;91m\]"
LIGHT_GREEN="\[\033[0;92m\]"
      WHITE="\[\033[0;97m\]"
 COLOR_NONE="\[\e[0m\]"

# Detect whether the current directory is a git repository.
function is_git_repository {
    git branch > /dev/null 2>&1
}

function is_rbenv_exist {
    rbenv version-name > /dev/null 2>&1 
}

function is_node_exist {
    node -v > /dev/null 2>&1
}

# Determine the branch/state information for this git repository.
function set_git_branch {
  # Capture the output of the "git status" command.
  git_status="$(git status 2> /dev/null)"

  # Set color based on clean/staged/dirty.
  if [[ ${git_status} =~ "working tree clean" ]]; then
    state="${GREEN}"
  elif [[ ${git_status} =~ "Changes to be committed" ]]; then
    state="${YELLOW}"
  else
    state="${RED}"
  fi

  # Set arrow icon based on status against remote.
  remote_pattern="Your branch is (.*) of"
  if [[ ${git_status} =~ ${remote_pattern} ]]; then
    if [[ ${BASH_REMATCH[1]} == "ahead" ]]; then
      remote="↑"
    else
      remote="↓"
    fi
  else
    remote=""
  fi
  diverge_pattern="Your branch and (.*) have diverged"
  if [[ ${git_status} =~ ${diverge_pattern} ]]; then
    remote="↕"
  fi

  # Get the name of the branch.
  branch_pattern="^On branch ([^${IFS}]*)"
  if [[ ${git_status} =~ ${branch_pattern} ]]; then
    branch=${BASH_REMATCH[1]}
  fi

  # Set the final branch string.
  BRANCH="${state}(${branch})${remote}${COLOR_NONE} "
}

# Return the prompt symbol to use, colorized based on the return value of the
# previous command.
function set_prompt_symbol () {
  if test $1 -eq 0 ; then
      PROMPT_SYMBOL="${COLOR_NONE}\$"
  else
      PROMPT_SYMBOL="${RED}\$${COLOR_NONE}"
  fi
}

# Set the full bash prompt.
function set_bash_prompt () {
    # Set the PROMPT_SYMBOL variable. We do this first so we don't lose the
    # return value of the last command.
    set_prompt_symbol $?

    # Set the BRANCH variable.
    if is_git_repository ; then
        set_git_branch
    else
        BRANCH=''
    fi

    if is_rbenv_exist ; then
        rbv=ruby-v`rbenv version-name`
        RBV="${LIGHT_RED}${rbv}"
    else
        RBV=''
    fi
    
    if is_node_exist ; then
        ndv=node-`node -v`
        NDV="${BLUE}${ndv}"
    else
        NDV=''
    fi
    # Set the bash prompt variable.
    # PS1="\u@\h \w ${BRANCH}${PROMPT_SYMBOL} "
    PS1="${GREEN}\u${YELLOW}@\W:${RBV}${COLOR_NONE}·${NDV}${BRANCH}${PROMPT_SYMBOL}\n-> "
}

# Tell bash to execute this function just before displaying its prompt.
PROMPT_COMMAND=set_bash_prompt