方法1.

function git_branch {
   branch="`git branch 2>/dev/null | grep "^\*" | sed -e "s/^\*\ //"`"
   if [ "${branch}" != "" ];then
       if [ $branch == *"HEAD"* ];then
           branch="`git rev-parse --short HEAD`"
       fi
       echo "($branch)"
   fi
}

export PS1='\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[01;32m\]$(git_branch)\[\033[00m\]\$'

方法2.

PS1='\u@\h:\w$(__git_ps1 " (%s)")\$ '