Adds color, git repository, and virtualenv information to command line prompt

bash_prompt

#!/bin/bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the active virtualenv
#    * the branch/status of the current git repository
#    * the return value of the previous command
#    * the fact you just came from Windows and are used to having newlines in
#      your prompts.
#
# USAGE:
#
#   1. Save this file as ~/.bash_prompt
#   2. Add the following line to the end of your ~/.bashrc or ~/.bash_profile:
#        . ~/.bash_prompt
#
# LINEAGE:
#
#   Based on work by woods
#
#   https://gist.github.com/31967

# The various escape codes that we can use to color our prompt.
# @NOTE:  I've mapped these codes out according to how ``Terminator`` displays them.
#   Other editors may be different.
ROW_0="\[\033[0;"
ROW_1="\[\033[1;"
COLUMN_0="30m\]"
COLUMN_1="31m\]"
COLUMN_2="32m\]"
COLUMN_3="33m\]"
COLUMN_4="34m\]"
COLUMN_5="35m\]"
COLUMN_6="36m\]"
COLUMN_7="37m\]"


COLOR_NONE="\[\e[0m\]"


# You may map the colors to a readable name if your color scheme is not based off of the standard palette.  
# This will make your code MUCH easier to read. If you change a color in your color scheme, 
# you can simply find/replace the name in this file.
#
# I used ``gpick`` to find my color names -- This color scheme is based off of ``Monokai``.
#          BLACK=${ROW_0}${COLUMN_0}
# BLEACHED_CEDAR=${ROW_1}${COLUMN_0}
#            RED=${ROW_0}${COLUMN_1}
#         VIOLET=${ROW_1}${COLUMN_1}
#           LIME=${ROW_0}${COLUMN_2}
#    LIGHT_GREEN=${ROW_1}${COLUMN_2}
#    DARK_ORANGE=${ROW_0}${COLUMN_3}
#      PORTAFINO=${ROW_1}${COLUMN_3}
#     CORNFLOWER=${ROW_0}${COLUMN_4}
#       SKY_BLUE=${ROW_1}${COLUMN_4}
#         PURPLE=${ROW_0}${COLUMN_5}
#    DODGER_BLUE=${ROW_1}${COLUMN_5}
#      SEA_GREEN=${ROW_0}${COLUMN_6}
#      TURQUOISE=${ROW_1}${COLUMN_6}
#       DIM_GRAY=${ROW_0}${COLUMN_7}
#         GEYSER=${ROW_1}${COLUMN_7}


# Standard color map
       GRAY=${ROW_0}${COLUMN_0}
  BOLD_GRAY=${ROW_1}${COLUMN_0}
        RED=${ROW_0}${COLUMN_1}
   BOLD_RED=${ROW_1}${COLUMN_1}
      GREEN=${ROW_0}${COLUMN_2}
 BOLD_GREEN=${ROW_1}${COLUMN_2}
     YELLOW=${ROW_0}${COLUMN_3}
BOLD_YELLOW=${ROW_1}${COLUMN_3}
       BLUE=${ROW_0}${COLUMN_4}
  BOLD_BLUE=${ROW_1}${COLUMN_4}
     PURPLE=${ROW_0}${COLUMN_5}
BOLD_PURPLE=${ROW_1}${COLUMN_5}
       CYAN=${ROW_0}${COLUMN_6}
  BOLD_CYAN=${ROW_1}${COLUMN_6}
     SILVER=${ROW_0}${COLUMN_7}
BOLD_SILVER=${ROW_1}${COLUMN_7}



# Detect whether the current directory is a git repository.
function is_git_repository {
  git branch > /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 directory clean" ]]; then
    state=""
  elif [[ ${git_status} =~ "Changes to be committed" ]]; then
    state="+"
  else
    state="*"
  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="(${YELLOW}${branch}${state}${COLOR_NONE})${PURPLE}${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 $1 -eq 0 ; then
      PROMPT_SYMBOL="\$"
  else
      PROMPT_SYMBOL="${BOLD_RED}\$${COLOR_NONE}"
  fi
}

# Determine active Python virtualenv details.
function set_virtualenv () {
  if test -z "$VIRTUAL_ENV" ; then
      PYTHON_VIRTUALENV=""
  else
      PYTHON_VIRTUALENV="[${RED}`basename \"$VIRTUAL_ENV\"`${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 PYTHON_VIRTUALENV variable.
  set_virtualenv

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

  # Set the bash prompt variable.
  PS1="\n${PYTHON_VIRTUALENV}${BOLD_BLUE}\u@\h${COLOR_NONE}:${BOLD_GREEN}\w${COLOR_NONE} ${BRANCH}${COLOR_NONE}\n${PROMPT_SYMBOL} "
}

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