Change the zsh (or other shell) PROMPT to contain basic git status information

.zshrc

function git_status() {
  if git status >/dev/null 2>/dev/null; then
    status_str=`git status -s 2>/dev/null | cut -f1 -d' ' | uniq -c | awk '{ print $2 " " $1 }' | paste -s -d' '`
    branch=`git branch --show-current`
    commit_hash=`git log -1 --format=%h`
    echo "[git: $commit_hash $branch $status_str]"
  fi
}

# important (!)
setopt PROMPT_SUBST

export __GIT_STATUS='$(git_status)'

export PROMPT="... $__GIT_STATUS ..."