A two-line colored Bash prompt (PS1) with Git branch and a line decoration which adjusts automatically to the width of the terminal. Recognizes SVN, Git and Fossil version control systems and shows the current branch/revision.

twoline_prompt.sh

# A two-line colored Bash prompt (PS1) with Git branch and a line decoration
# which adjusts automatically to the width of the terminal.
# Recognizes and shows Git, SVN and Fossil branch/revision.
# Screenshot: http://img194.imageshack.us/img194/2154/twolineprompt.png
# Michal Kottman, 2012
 
RESET="\[\033[0m\]"
RED="\[\033[0;31m\]"
GREEN="\[\033[01;32m\]"
BLUE="\[\033[01;34m\]"
YELLOW="\[\033[0;33m\]"
 
PS_LINE=`printf -- '- %.0s' {1..200}`
function parse_git_branch {
  PS_BRANCH=''
  PS_FILL=${PS_LINE:0:$COLUMNS}
  if [ -d .svn ]; then
    PS_BRANCH="(svn r$(svn info|awk '/Revision/{print $2}'))"
    return
  elif [ -f _FOSSIL_ -o -f .fslckout ]; then
    PS_BRANCH="(fossil $(fossil status|awk '/tags/{print $2}')) "
    return
  fi
  ref=$(git symbolic-ref HEAD 2> /dev/null) || return
  PS_BRANCH="(git ${ref#refs/heads/}) "
}
PROMPT_COMMAND=parse_git_branch
PS_INFO="$GREEN\u@\h$RESET:$BLUE\w"
PS_GIT="$YELLOW\$PS_BRANCH"
PS_TIME="\[\033[\$((COLUMNS-10))G\] $RED[\t]"
export PS1="\${PS_FILL}\[\033[0G\]${PS_INFO} ${PS_GIT}${PS_TIME}\n${RESET}\$ "

To have correct # vs $ while sudo -s, in the last line we had to use single quotes around $:
export PS1="\${PS_FILL}\[\033[0G\]${PS_INFO} ${PS_GIT}${PS_TIME}\n${RESET}"'\$ '

or one can just quote the backslash before the last $: "...\n${RESET}\\$ "

I am now using https://github.com/juhp/configuration/blob/b6e03ca0b375ac82deedfd5ab86a83b98327b45e/bash/bashrc#L48

Are \[ and \] explained somewhere?

Ho handle git unborn repo (newly created) and git detached HEAD, I replaced lines 24 and 25 with;

    branches=$(git branch 2> /dev/null) || return
    ref=$(echo "$branches" | grep "^*" | sed -e 's/^* //')
    [ "x${ref}" = "x" ] && ref="unborn: $(git symbolic-ref HEAD | sed -e 's#refs/heads/##')"
    PS_BRANCH="[git: ${ref}] "