git + python virtualenv bash PROMPT_COMMAND

.bash_prompt

#!/bin/bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the active virtualenv
#    * the branch of the current git/mercurial 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

. /usr/lib/git-core/git-sh-prompt
# git-sh-prompt options
GIT_PS1_SHOWDIRTYSTATE=1
GIT_PS1_SHOWSTASHSTATE=1
GIT_PS1_SHOWUNTRACKEDFILES=1
# Explicitly unset color (default anyhow). Use 1 to set it.
GIT_PS1_SHOWCOLORHINTS=1
GIT_PS1_DESCRIBE_STYLE="branch"
GIT_PS1_SHOWUPSTREAM="auto git"

get_sha() {
    git rev-parse --short HEAD 2>/dev/null
}

# The various escape codes that we can use to color our prompt.
        RED="\[\033[0;31m\]"
     YELLOW="\[\033[1;33m\]"
      GREEN="\[\033[0;32m\]"
       BLUE="\[\033[1;34m\]"
     PURPLE="\[\033[0;35m\]"
  LIGHT_RED="\[\033[1;31m\]"
LIGHT_GREEN="\[\033[1;32m\]"
      WHITE="\[\033[1;37m\]"
 LIGHT_GRAY="\[\033[0;37m\]"
 COLOR_NONE="\[\e[0m\]"

# previous command.
function set_prompt_symbol () {
  if test $1 -eq 0 ; then
      PROMPT_SYMBOL="\$"
  else
      PROMPT_SYMBOL="${LIGHT_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 bash prompt variable.
  PS1="${PYTHON_VIRTUALENV}${GREEN}\u@\h${COLOR_NONE}:${YELLOW}\w${COLOR_NONE}$(__git_ps1 " [%s $(get_sha)]")
${PROMPT_SYMBOL} "
}

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