Set color bash prompt according to git/svn branch, and return status of last command. Now with better readable colors, much cooler shell prompt and xterm title override.

git_svn_bash_prompt.sh

#!/bin/bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the branch/status of the current git repository
#    * the branch of the current subversion repository
#    * the return value of the previous command
#
# USAGE:
#
#   1. Save this file as ~/.git_svn_bash_prompt
#   2. Add the following line to the end of your ~/.bash_profile:
#        . ~/.git_svn_bash_prompt
#
# AUTHOR:
#
#   Scott Woods <scott@westarete.com>
#   West Arete Computing
#
#   Based on work by halbtuerke and lakiolen.
#
#   http://gist.github.com/31967


# The various escape codes that we can use to color our prompt.
        RED='\[\e[31;1m\]'
     YELLOW='\[\e[33;1m\]'
      GREEN='\[\e[32;1m\]'
       BLUE='\[\e[34;1m\]'
      WHITE='\[\e[0;1m\]'
       GRAY='\[\e[37;1m\]'
       CYAN='\[\e[36;1m\]'
     VIOLET='\[\e[35;1m\]'
 COLOR_NONE='\[\e[0m\]'

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

# Detect whether the current directory is a subversion repository.
function is_svn_repository {
  test -d .svn
}

# Determine the branch/state information for this git repository.
function set_git_branch {
  # Capture the output of the "git status" command.
  git_status="$(LANG=en_GB.UTF-8 git status 2> /dev/null)"

  # Set color based on clean/staged/dirty.
  if [[ ${git_status} =~ "HEAD detached at" ]]; then
    state="${VIOLET}"
  elif [[ ${git_status} =~ "working tree clean" ]]; then
    state="${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

  # Or get the tag
  tag_pattern="^HEAD detached at ([^${IFS}]*)"
  if [[ ${git_status} =~ ${tag_pattern} ]]; then
    branch=${BASH_REMATCH[1]}
  fi

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

# Determine the branch information for this subversion repository. No support
# for svn status, since that needs to hit the remote repository.
function set_svn_branch {
  # Capture the output of the "git status" command.
  svn_info="$(LANG=en_GB.UTF-8 svn info | egrep '^URL: ' 2> /dev/null)"

  # Get the name of the branch.
  branch_pattern="^URL: .*/(branches|tags)/([^/]+)"
  trunk_pattern="^URL: .*/trunk(/.*)?$"
  if [[ ${svn_info} =~ $branch_pattern ]]; then
    branch=${BASH_REMATCH[2]}
  elif [[ ${svn_info} =~ $trunk_pattern ]]; then
    branch='trunk'
  fi

  # Set the final branch string.
  BRANCH="(${branch}) "
  BRANCH_NC="(${branch})"
}

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

  actual_dir="$(pwd)"

  if [[ ${actual_dir} =~ "/var/run/user" ]]; then
    BRANCH=''
    BRANCH_NC=''
  else
    # Set the BRANCH variable.
    if is_git_repository ; then
      set_git_branch
    elif is_svn_repository ; then
      set_svn_branch
    else
      BRANCH=''
    BRANCH_NC=''
    fi
  fi

  # Set the bash prompt variable.
  PS1="${PROMPT_COLOR}┌─( ${RED}${debian_chroot:+($debian_chroot)}\u${YELLOW}@${CYAN}\h${PROMPT_COLOR} ) - ( ${YELLOW}\w${PROMPT_COLOR} ) ${BRANCH}\n${PROMPT_COLOR}└──┤ ${COLOR_NONE}"
  PS2="${PROMPT_COLOR}   │ ${COLOR_NONE}"

  # If this is an xterm set the title to user@host:dir
  case "$TERM" in
  xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w ${BRANCH_NC}\a\]$PS1"
    ;;
  *)
    ;;
  esac
}

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