Bash git prompt (show current git branch in prompt)

git-prompt.sh

# bash/zsh git prompt support
#
# Copyright (C) 2006,2007 Shawn O. Pearce <spearce@spearce.org>
# Distributed under the GNU General Public License, version 2.0.
#
# This script allows you to see repository status in your prompt.
#
# To enable:
#
#    1) Copy this file to somewhere (e.g. ~/.git-prompt.sh).
#    2) Add the following line to your .bashrc/.zshrc:
#        source ~/.git-prompt.sh
#    3a) Change your PS1 to call __git_ps1 as
#        command-substitution:
#        Bash: PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
#        ZSH:  setopt PROMPT_SUBST ; PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
#        the optional argument will be used as format string.
#    3b) Alternatively, for a slightly faster prompt, __git_ps1 can
#        be used for PROMPT_COMMAND in Bash or for precmd() in Zsh
#        with two parameters, <pre> and <post>, which are strings
#        you would put in $PS1 before and after the status string
#        generated by the git-prompt machinery.  e.g.
#        Bash: PROMPT_COMMAND='__git_ps1 "\u@\h:\w" "\\\$ "'
#          will show username, at-sign, host, colon, cwd, then
#          various status string, followed by dollar and SP, as
#          your prompt.
#        ZSH:  precmd () { __git_ps1 "%n" ":%~$ " "|%s" }
#          will show username, pipe, then various status string,
#          followed by colon, cwd, dollar and SP, as your prompt.
#        Optionally, you can supply a third argument with a printf
#        format string to finetune the output of the branch status
#
# The repository status will be displayed only if you are currently in a
# git repository. The %s token is the placeholder for the shown status.
#
# The prompt status always includes the current branch name.
#
# In addition, if you set GIT_PS1_SHOWDIRTYSTATE to a nonempty value,
# unstaged (*) and staged (+) changes will be shown next to the branch
# name.  You can configure this per-repository with the
# bash.showDirtyState variable, which defaults to true once
# GIT_PS1_SHOWDIRTYSTATE is enabled.
#
# You can also see if currently something is stashed, by setting
# GIT_PS1_SHOWSTASHSTATE to a nonempty value. If something is stashed,
# then a '$' will be shown next to the branch name.
#
# If you would like to see if there're untracked files, then you can set
# GIT_PS1_SHOWUNTRACKEDFILES to a nonempty value. If there're untracked
# files, then a '%' will be shown next to the branch name.  You can
# configure this per-repository with the bash.showUntrackedFiles
# variable, which defaults to true once GIT_PS1_SHOWUNTRACKEDFILES is
# enabled.
#
# If you would like to see the difference between HEAD and its upstream,
# set GIT_PS1_SHOWUPSTREAM="auto".  A "<" indicates you are behind, ">"
# indicates you are ahead, "<>" indicates you have diverged and "="
# indicates that there is no difference. You can further control
# behaviour by setting GIT_PS1_SHOWUPSTREAM to a space-separated list
# of values:
#
#     verbose       show number of commits ahead/behind (+/-) upstream
#     name          if verbose, then also show the upstream abbrev name
#     legacy        don't use the '--count' option available in recent
#                   versions of git-rev-list
#     git           always compare HEAD to @{upstream}
#     svn           always compare HEAD to your SVN upstream
#
# By default, __git_ps1 will compare HEAD to your SVN upstream if it can
# find one, or @{upstream} otherwise.  Once you have set
# GIT_PS1_SHOWUPSTREAM, you can override it on a per-repository basis by
# setting the bash.showUpstream config variable.
#
# If you would like to see more information about the identity of
# commits checked out as a detached HEAD, set GIT_PS1_DESCRIBE_STYLE
# to one of these values:
#
#     contains      relative to newer annotated tag (v1.6.3.2~35)
#     branch        relative to newer tag or branch (master~4)
#     describe      relative to older annotated tag (v1.6.3.1-13-gdd42c2f)
#     default       exactly matching tag
#
# If you would like a colored hint about the current dirty state, set
# GIT_PS1_SHOWCOLORHINTS to a nonempty value. The colors are based on
# the colored output of "git status -sb" and are available only when
# using __git_ps1 for PROMPT_COMMAND or precmd.
#
# If you would like __git_ps1 to do nothing in the case when the current
# directory is set up to be ignored by git, then set
# GIT_PS1_HIDE_IF_PWD_IGNORED to a nonempty value. Override this on the
# repository level by setting bash.hideIfPwdIgnored to "false".

# check whether printf supports -v
__git_printf_supports_v=
printf -v __git_printf_supports_v -- '%s' yes >/dev/null 2>&1

# stores the divergence from upstream in $p
# used by GIT_PS1_SHOWUPSTREAM
__git_ps1_show_upstream ()
{
  local key value
  local svn_remote svn_url_pattern count n
  local upstream=git legacy="" verbose="" name=""

  svn_remote=()
  # get some config options from git-config
  local output="$(git config -z --get-regexp '^(svn-remote\..*\.url|bash\.showupstream)$' 2>/dev/null | tr '\0\n' '\n ')"
  while read -r key value; do
    case "$key" in
    bash.showupstream)
      GIT_PS1_SHOWUPSTREAM="$value"
      if [[ -z "${GIT_PS1_SHOWUPSTREAM}" ]]; then
        p=""
        return
      fi
      ;;
    svn-remote.*.url)
      svn_remote[$((${#svn_remote[@]} + 1))]="$value"
      svn_url_pattern="$svn_url_pattern\\|$value"
      upstream=svn+git # default upstream is SVN if available, else git
      ;;
    esac
  done <<< "$output"

  # parse configuration values
  for option in ${GIT_PS1_SHOWUPSTREAM}; do
    case "$option" in
    git|svn) upstream="$option" ;;
    verbose) verbose=1 ;;
    legacy)  legacy=1  ;;
    name)    name=1 ;;
    esac
  done

  # Find our upstream
  case "$upstream" in
  git)    upstream="@{upstream}" ;;
  svn*)
    # get the upstream from the "git-svn-id: ..." in a commit message
    # (git-svn uses essentially the same procedure internally)
    local -a svn_upstream
    svn_upstream=($(git log --first-parent -1 \
          --grep="^git-svn-id: \(${svn_url_pattern#??}\)" 2>/dev/null))
    if [[ 0 -ne ${#svn_upstream[@]} ]]; then
      svn_upstream=${svn_upstream[${#svn_upstream[@]} - 2]}
      svn_upstream=${svn_upstream%@*}
      local n_stop="${#svn_remote[@]}"
      for ((n=1; n <= n_stop; n++)); do
        svn_upstream=${svn_upstream#${svn_remote[$n]}}
      done

      if [[ -z "$svn_upstream" ]]; then
        # default branch name for checkouts with no layout:
        upstream=${GIT_SVN_ID:-git-svn}
      else
        upstream=${svn_upstream#/}
      fi
    elif [[ "svn+git" = "$upstream" ]]; then
      upstream="@{upstream}"
    fi
    ;;
  esac

  # Find how many commits we are ahead/behind our upstream
  if [[ -z "$legacy" ]]; then
    count="$(git rev-list --count --left-right \
        "$upstream"...HEAD 2>/dev/null)"
  else
    # produce equivalent output to --count for older versions of git
    local commits
    if commits="$(git rev-list --left-right "$upstream"...HEAD 2>/dev/null)"
    then
      local commit behind=0 ahead=0
      for commit in $commits
      do
        case "$commit" in
        "<"*) ((behind++)) ;;
        *)    ((ahead++))  ;;
        esac
      done
      count="$behind  $ahead"
    else
      count=""
    fi
  fi

  # calculate the result
  if [[ -z "$verbose" ]]; then
    case "$count" in
    "") # no upstream
      p="" ;;
    "0  0") # equal to upstream
      p="=" ;;
    "0  "*) # ahead of upstream
      p=">" ;;
    *"  0") # behind upstream
      p="<" ;;
    *)      # diverged from upstream
      p="<>" ;;
    esac
  else
    case "$count" in
    "") # no upstream
      p="" ;;
    "0  0") # equal to upstream
      p=" u=" ;;
    "0  "*) # ahead of upstream
      p=" u+${count#0 }" ;;
    *"  0") # behind upstream
      p=" u-${count%  0}" ;;
    *)      # diverged from upstream
      p=" u+${count#* }-${count%  *}" ;;
    esac
    if [[ -n "$count" && -n "$name" ]]; then
      __git_ps1_upstream_name=$(git rev-parse \
        --abbrev-ref "$upstream" 2>/dev/null)
      if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
        p="$p \${__git_ps1_upstream_name}"
      else
        p="$p ${__git_ps1_upstream_name}"
        # not needed anymore; keep user's
        # environment clean
        unset __git_ps1_upstream_name
      fi
    fi
  fi

}

# Helper function that is meant to be called from __git_ps1.  It
# injects color codes into the appropriate gitstring variables used
# to build a gitstring.
__git_ps1_colorize_gitstring ()
{
  if [[ -n ${ZSH_VERSION-} ]]; then
    local c_red='%F{red}'
    local c_green='%F{green}'
    local c_lblue='%F{blue}'
    local c_clear='%f'
  else
    # Using \[ and \] around colors is necessary to prevent
    # issues with command line editing/browsing/completion!
    local c_red='\[\e[31m\]'
    local c_green='\[\e[32m\]'
    local c_lblue='\[\e[1;34m\]'
    local c_clear='\[\e[0m\]'
  fi
  local bad_color=$c_red
  local ok_color=$c_green
  local flags_color="$c_lblue"

  local branch_color=""
  if [ $detached = no ]; then
    branch_color="$ok_color"
  else
    branch_color="$bad_color"
  fi
  c="$branch_color$c"

  z="$c_clear$z"
  if [ "$w" = "*" ]; then
    w="$bad_color$w"
  fi
  if [ -n "$i" ]; then
    i="$ok_color$i"
  fi
  if [ -n "$s" ]; then
    s="$flags_color$s"
  fi
  if [ -n "$u" ]; then
    u="$bad_color$u"
  fi
  r="$c_clear$r"
}

__git_eread ()
{
  local f="$1"
  shift
  test -r "$f" && read "$@" <"$f"
}

# __git_ps1 accepts 0 or 1 arguments (i.e., format string)
# when called from PS1 using command substitution
# in this mode it prints text to add to bash PS1 prompt (includes branch name)
#
# __git_ps1 requires 2 or 3 arguments when called from PROMPT_COMMAND (pc)
# in that case it _sets_ PS1. The arguments are parts of a PS1 string.
# when two arguments are given, the first is prepended and the second appended
# to the state string when assigned to PS1.
# The optional third parameter will be used as printf format string to further
# customize the output of the git-status string.
# In this mode you can request colored hints using GIT_PS1_SHOWCOLORHINTS=true
__git_ps1 ()
{
  # preserve exit status
  local exit=$?
  local pcmode=no
  local detached=no
  local ps1pc_start='\u@\h:\w '
  local ps1pc_end='\$ '
  local printf_format=' (%s)'

  case "$#" in
    2|3)  pcmode=yes
      ps1pc_start="$1"
      ps1pc_end="$2"
      printf_format="${3:-$printf_format}"
      # set PS1 to a plain prompt so that we can
      # simply return early if the prompt should not
      # be decorated
      PS1="$ps1pc_start$ps1pc_end"
    ;;
    0|1)  printf_format="${1:-$printf_format}"
    ;;
    *)  return $exit
    ;;
  esac

  # ps1_expanded:  This variable is set to 'yes' if the shell
  # subjects the value of PS1 to parameter expansion:
  #
  #   * bash does unless the promptvars option is disabled
  #   * zsh does not unless the PROMPT_SUBST option is set
  #   * POSIX shells always do
  #
  # If the shell would expand the contents of PS1 when drawing
  # the prompt, a raw ref name must not be included in PS1.
  # This protects the user from arbitrary code execution via
  # specially crafted ref names.  For example, a ref named
  # 'refs/heads/$(IFS=_;cmd=sudo_rm_-rf_/;$cmd)' might cause the
  # shell to execute 'sudo rm -rf /' when the prompt is drawn.
  #
  # Instead, the ref name should be placed in a separate global
  # variable (in the __git_ps1_* namespace to avoid colliding
  # with the user's environment) and that variable should be
  # referenced from PS1.  For example:
  #
  #     __git_ps1_foo=$(do_something_to_get_ref_name)
  #     PS1="...stuff...\${__git_ps1_foo}...stuff..."
  #
  # If the shell does not expand the contents of PS1, the raw
  # ref name must be included in PS1.
  #
  # The value of this variable is only relevant when in pcmode.
  #
  # Assume that the shell follows the POSIX specification and
  # expands PS1 unless determined otherwise.  (This is more
  # likely to be correct if the user has a non-bash, non-zsh
  # shell and safer than the alternative if the assumption is
  # incorrect.)
  #
  local ps1_expanded=yes
  [ -z "$ZSH_VERSION" ] || [[ -o PROMPT_SUBST ]] || ps1_expanded=no
  [ -z "$BASH_VERSION" ] || shopt -q promptvars || ps1_expanded=no

  local repo_info rev_parse_exit_code
  repo_info="$(git rev-parse --git-dir --is-inside-git-dir \
    --is-bare-repository --is-inside-work-tree \
    --short HEAD 2>/dev/null)"
  rev_parse_exit_code="$?"

  if [ -z "$repo_info" ]; then
    return $exit
  fi

  local short_sha
  if [ "$rev_parse_exit_code" = "0" ]; then
    short_sha="${repo_info##*$'\n'}"
    repo_info="${repo_info%$'\n'*}"
  fi
  local inside_worktree="${repo_info##*$'\n'}"
  repo_info="${repo_info%$'\n'*}"
  local bare_repo="${repo_info##*$'\n'}"
  repo_info="${repo_info%$'\n'*}"
  local inside_gitdir="${repo_info##*$'\n'}"
  local g="${repo_info%$'\n'*}"

  if [ "true" = "$inside_worktree" ] &&
     [ -n "${GIT_PS1_HIDE_IF_PWD_IGNORED-}" ] &&
     [ "$(git config --bool bash.hideIfPwdIgnored)" != "false" ] &&
     git check-ignore -q .
  then
    return $exit
  fi

  local r=""
  local b=""
  local step=""
  local total=""
  if [ -d "$g/rebase-merge" ]; then
    __git_eread "$g/rebase-merge/head-name" b
    __git_eread "$g/rebase-merge/msgnum" step
    __git_eread "$g/rebase-merge/end" total
    if [ -f "$g/rebase-merge/interactive" ]; then
      r="|REBASE-i"
    else
      r="|REBASE-m"
    fi
  else
    if [ -d "$g/rebase-apply" ]; then
      __git_eread "$g/rebase-apply/next" step
      __git_eread "$g/rebase-apply/last" total
      if [ -f "$g/rebase-apply/rebasing" ]; then
        __git_eread "$g/rebase-apply/head-name" b
        r="|REBASE"
      elif [ -f "$g/rebase-apply/applying" ]; then
        r="|AM"
      else
        r="|AM/REBASE"
      fi
    elif [ -f "$g/MERGE_HEAD" ]; then
      r="|MERGING"
    elif [ -f "$g/CHERRY_PICK_HEAD" ]; then
      r="|CHERRY-PICKING"
    elif [ -f "$g/REVERT_HEAD" ]; then
      r="|REVERTING"
    elif [ -f "$g/BISECT_LOG" ]; then
      r="|BISECTING"
    fi

    if [ -n "$b" ]; then
      :
    elif [ -h "$g/HEAD" ]; then
      # symlink symbolic ref
      b="$(git symbolic-ref HEAD 2>/dev/null)"
    else
      local head=""
      if ! __git_eread "$g/HEAD" head; then
        return $exit
      fi
      # is it a symbolic ref?
      b="${head#ref: }"
      if [ "$head" = "$b" ]; then
        detached=yes
        b="$(
        case "${GIT_PS1_DESCRIBE_STYLE-}" in
        (contains)
          git describe --contains HEAD ;;
        (branch)
          git describe --contains --all HEAD ;;
        (describe)
          git describe HEAD ;;
        (* | default)
          git describe --tags --exact-match HEAD ;;
        esac 2>/dev/null)" ||

        b="$short_sha..."
        b="($b)"
      fi
    fi
  fi

  if [ -n "$step" ] && [ -n "$total" ]; then
    r="$r $step/$total"
  fi

  local w=""
  local i=""
  local s=""
  local u=""
  local c=""
  local p=""

  if [ "true" = "$inside_gitdir" ]; then
    if [ "true" = "$bare_repo" ]; then
      c="BARE:"
    else
      b="GIT_DIR!"
    fi
  elif [ "true" = "$inside_worktree" ]; then
    if [ -n "${GIT_PS1_SHOWDIRTYSTATE-}" ] &&
       [ "$(git config --bool bash.showDirtyState)" != "false" ]
    then
      git diff --no-ext-diff --quiet --exit-code || w="*"
      if [ -n "$short_sha" ]; then
        git diff-index --cached --quiet HEAD -- || i="+"
      else
        i="#"
      fi
    fi
    if [ -n "${GIT_PS1_SHOWSTASHSTATE-}" ] &&
       git rev-parse --verify --quiet refs/stash >/dev/null
    then
      s="$"
    fi

    if [ -n "${GIT_PS1_SHOWUNTRACKEDFILES-}" ] &&
       [ "$(git config --bool bash.showUntrackedFiles)" != "false" ] &&
       git ls-files --others --exclude-standard --error-unmatch -- ':/*' >/dev/null 2>/dev/null
    then
      u="%${ZSH_VERSION+%}"
    fi

    if [ -n "${GIT_PS1_SHOWUPSTREAM-}" ]; then
      __git_ps1_show_upstream
    fi
  fi

  local z="${GIT_PS1_STATESEPARATOR-" "}"

  # NO color option unless in PROMPT_COMMAND mode
  if [ $pcmode = yes ] && [ -n "${GIT_PS1_SHOWCOLORHINTS-}" ]; then
    __git_ps1_colorize_gitstring
  fi

  b=${b##refs/heads/}
  if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
    __git_ps1_branch_name=$b
    b="\${__git_ps1_branch_name}"
  fi

  local f="$w$i$s$u"
  local gitstring="$c$b${f:+$z$f}$r$p"

  if [ $pcmode = yes ]; then
    if [ "${__git_printf_supports_v-}" != yes ]; then
      gitstring=$(printf -- "$printf_format" "$gitstring")
    else
      printf -v gitstring -- "$printf_format" "$gitstring"
    fi
    PS1="$ps1pc_start$gitstring$ps1pc_end"
  else
    printf -- "$printf_format" "$gitstring"
  fi

  return $exit
}