bash_prompt.sh

#!/bin/bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the active virtualenv
#    * the branch/status of the current mercurial repository
#    * the return value of the previous command
#
# USAGE:
#
#   1. Save this file as ~/.bash_prompt
#   2. Add the following line to the end of your ~/.bashrc or ~/.bash_profile or ~/.profile:
#        . ~/.bash_prompt
#
# LINEAGE:
#
#   Based on work by insin
#
#   https://gist.github.com/1425703

# The various escape codes that we can use to color our prompt.
     YELLOW="\[\033[0;33m\]"
      GREEN="\[\033[0;32m\]"
       BLUE="\[\033[0;34m\]"
        RED="\[\033[1;31m\]"
 COLOR_NONE="\[\e[0m\]"

# Determine the branch/state information for this mercurial repository.
function set_hg_branch {
  # Get the name of the branch.
  branch=$(hg branch 2>/dev/null)
  # Default state
  state="${GREEN}"

  if [ -n "${branch}" ]; then
    branch=" (${branch})"

    # Capture the output of the "hg status" command.
    hg_status="$(hg status | wc -l)"

    # Set color based on clean/staged/dirty.
    if [ "${hg_status}" -ne "0" ]; then
      state="${RED}"
    fi
  fi

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

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

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

  # Set the bash prompt variable.
  PS1="${PYTHON_VIRTUALENV}${GREEN}\h:${YELLOW}\w${COLOR_NONE}${BRANCH}${PROMPT_SYMBOL} "
}

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