git_prompt.sh

#!/bin/bash

function parse_git_branch () {
  if [[ -z $(git status --porcelain) ]]; then
    echo -ne "\001\033[0;32m\002"
  else
    echo -ne "\001\033[1;31m\002"
  fi
  BRANCH=`git branch 2>/dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/\1/'`
  echo -n $BRANCH
  REMOTE=`git for-each-ref --format='%(upstream:short)' $(git symbolic-ref -q HEAD)`
  if [ "$REMOTE" != "" ]; then
    AHEAD=`git rev-list $REMOTE..HEAD | wc -l`   # If you have git >=1.8: replace '| wc -l' by '--count'
    BEHIND=`git rev-list HEAD..$REMOTE | wc -l`  # same
    if [ "$BEHIND" != "0" ]; then echo -ne "\001\033[1;31m\002-$BEHIND"; fi
    if [ "$AHEAD" != "0" ]; then echo -ne "\001\033[1;32m\002+$AHEAD"; fi
  fi
}
alias __ps1_gitstat='echo -en "\001\033[1;33m\002[`parse_git_branch`\001\033[1;33m\002] "'

PS1="\[\033[1;31m\]\h \[\033[1;34m\]\W \`if [ \$? = 0 ]; then echo '\[\033[1;32m\]:)'; else echo '\[\033[1;31m\]:('; fi\` \`git rev-parse 2>/dev/null && __ps1_gitstat\`\[\033[0m\]\$ "