Bash prompt with Git Info

.bash_profile

# Function for determining current git branch (if any)
# Gracefully fails if not in a git repo and returns nothing.
__gitBranch() {
  ref=$(git symbolic-ref HEAD 2> /dev/null) || return
  echo ${ref#refs/heads/}
}

# Retrieves status information for git and places into predefined variables.
__gitStatus() {
    # Initialise git status variables
    __GIT_ADD=0
    __GIT_MOD=0
    __GIT_DEL=0
    __GIT_UNTRACKED=0
    __GIT_AHEAD=0
    
    while read line; do
        if [[ $line =~ (ahead of .origin/.* by ([0-9]+) commit.*) ]]  ; then
            __GIT_AHEAD=${BASH_REMATCH[2]}
        elif [[ $line =~ 'deleted:' ]]  ; then
            __GIT_DEL=$(( $__GIT_DEL + 1 ))
        elif [[ $line =~ 'modified:' || $line =~ 'renamed:' ]]  ; then
            __GIT_MOD=$(( $__GIT_MOD + 1 ))
        elif [[ $line =~ 'new file:' ]]  ; then
            __GIT_ADD=$(( $__GIT_ADD + 1 ))
        elif [[ $line =~ '# Untracked files:' ]]  ; then
            __GIT_UNTRACKED=1
        fi
    done <<< "`git status`"
}

# Logic for determining the contents and setting the prompt
__prompt() {
    __GIT_BRANCH=$(__gitBranch)                 # Current git branch (if any)?
    __PROMPT="\[\033[1;32m\]\u@\h \W"           # Default prompt (not in git repo)
    
    # Test whether we are in a git repo
    if [ "$__GIT_BRANCH" != "" ] ; then
        __gitStatus                             # Run git status function
        __PROMPT="$__PROMPT \[\033[1;33m\]["    # Open bracket
        
        # Set correct color for branch name and append name
        if [ $__GIT_AHEAD != 0 ] ; then
            __PROMPT="$__PROMPT\[\033[1;31m\]"  # Red
        else
            __PROMPT="$__PROMPT\[\033[1;36m\]"  # Cyan
        fi
        __PROMPT="$__PROMPT$__GIT_BRANCH\[\033[1;33m\]"
        
        # Added, modified, deleted
        __PROMPT="$__PROMPT +$__GIT_ADD ~$__GIT_MOD -$__GIT_DEL"
        
        # Untracked files present?
        if [ $__GIT_UNTRACKED != 0 ] ; then
            __PROMPT="$__PROMPT !"
        fi
        
        __PROMPT="$__PROMPT]\[\033[1;32m\]"     # Close bracket
    fi
    
    __PROMPT="$__PROMPT\$\[\033[0m\]"           # Add \$ and reset color
    
    export PS1="$__PROMPT "                     # Set prompt
}

# Export prompt command and other environment variables
export CLICOLOR=1
export PROMPT_COMMAND=__prompt