Bash Prompt

I think a person’s command-line prompt says a lot about them.  Some people have big fancy prompts with tidbits of data; some people have simple black & white prompts.  Some people like fancy or frivolous things like smiley and frowny faces based on the error status of the last command; some people are strictly utilitarian.  I mostly fall into the last category – I like some color with my prompts when possible, but otherwise I only want to see my name, server, cwd, and VCS branch (if any).

/etc/profile

...
if [ -n "${BASH_VERSION}" ] ; then
    # Newer bash ebuilds include /etc/bash/bashrc which will setup PS1
    # including color.  We leave out color here because not all
    # terminals support it.
    if [ -f /etc/bash/bashrc ] ; then
        # Bash login shells run only /etc/profile
        # Bash non-login shells run only /etc/bash/bashrc
        # Since we want to run /etc/bash/bashrc regardless, we source it 
        # from here.  It is unfortunate that there is no way to do 
        # this *after* the user's .bash_profile runs (without putting 
        # it in the user's dot-files), but it shouldn't make any 
        # difference.
        . /etc/bash/bashrc
    else
        PS1='\u@\h \w \$ '
    fi
else
    # Setup a bland default prompt.  Since this prompt should be useable
    # on color and non-color terminals, as well as shells that don't
    # understand sequences such as \h, don't put anything special in it.
    PS1="${USER:-$(whoami 2>/dev/null)}@$(uname -n 2>/dev/null) \$ "
fi
...

~/.bashrc

...
# Load in the git branch prompt script, and alter PS1 to include the
# current branch on the prompt
source ~/.git-prompt

# PS1 may include an extra space at the end, so trim it off so we can
# include the altered prompt and a space
PS1=${PS1/% /}'$(__git_ps1 " (%s)") '
...

The code for .git-prompt is a little longer, and credit goes to Shawn O. Pearce.  There’s probably a more-compact version somewhere but this works well-enough for my needs.

~/.git-prompt

# 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 the current branch 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$(__git_ps1 " (%s)")]\$ '
#        ZSH:  PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
#        the optional argument will be used as format string.
#    3b) Alternatively, if you are using bash, __git_ps1 can be
#        used for PROMPT_COMMAND with two parameters, <pre> and
#        <post>, which are strings you would put in $PS1 before
#        and after the status string generated by the git-prompt
#        machinery.  e.g.
#           PROMPT_COMMAND='__git_ps1 "\u@\h:\w" "\\\$ "'
#        will show username, at-sign, host, colon, cwd, then
#        various status string, followed by dollar and SP, as
#        your prompt.
#        Optionally, you can supply a third argument with a printf
#        format string to finetune the output of the branch status
#
# The argument to __git_ps1 will be displayed only if you are currently
# in a git repository.  The %s token will be the name of the current
# branch.
#
# In addition, if you set GIT_PS1_SHOWDIRTYSTATE to a nonempty value,
# unstaged (*) and staged (+) changes will be shown next to the branch
# name.  You can configure this per-repository with the
# bash.showDirtyState variable, which defaults to true once
# GIT_PS1_SHOWDIRTYSTATE is enabled.
#
# You can also see if currently something is stashed, by setting
# GIT_PS1_SHOWSTASHSTATE to a nonempty value. If something is stashed,
# then a '$' 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
#     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".

# __gitdir accepts 0 or 1 arguments (i.e., location)
# returns location of .git repo
__gitdir ()
{
    # Note: this function is duplicated in git-completion.bash
    # When updating it, make sure you update the other one to match.
    if [ -z "${1-}" ]; then
        if [ -n "${__git_dir-}" ]; then
            echo "$__git_dir"
        elif [ -n "${GIT_DIR-}" ]; then
            test -d "${GIT_DIR-}" || return 1
            echo "$GIT_DIR"
        elif [ -d .git ]; then
            echo .git
        else
            git rev-parse --git-dir 2>/dev/null
        fi
    elif [ -d "$1/.git" ]; then
        echo "$1/.git"
    else
        echo "$1"
    fi
}

# 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=""

    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)) ]="$value"
            svn_url_pattern+="\\|$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  ;;
        esac
    done

    # Find our upstream
    case "$upstream" in
    git)    upstream="@{upstream}" ;;
    svn*)
        # get the upstream from the "git-svn-id: ..." in a commit message
        # (git-svn uses essentially the same procedure internally)
        local svn_upstream=($(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
    fi

}


# __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 ()
{
    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:-$printf_format}"
        ;;
        0|1)    printf_format="${1:-$printf_format}"
        ;;
        *)  return
        ;;
    esac

    local g="$(__gitdir)"
    if [ -z "$g" ]; then
        if [ $pcmode = yes ]; then
            #In PC mode PS1 always needs to be set
            PS1="$ps1pc_start$ps1pc_end"
        fi
    else
        local r=""
        local b=""
        if [ -f "$g/rebase-merge/interactive" ]; then
            r="|REBASE-i"
            b="$(cat "$g/rebase-merge/head-name")"
        elif [ -d "$g/rebase-merge" ]; then
            r="|REBASE-m"
            b="$(cat "$g/rebase-merge/head-name")"
        else
            if [ -d "$g/rebase-apply" ]; then
                if [ -f "$g/rebase-apply/rebasing" ]; then
                    r="|REBASE"
                elif [ -f "$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/BISECT_LOG" ]; then
                r="|BISECTING"
            fi

            b="$(git symbolic-ref HEAD 2>/dev/null)" || {
                detached=yes
                b="$(
                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="$(cut -c1-7 "$g/HEAD" 2>/dev/null)..." ||
                b="unknown"
                b="($b)"
            }
        fi

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

        if [ "true" = "$(git rev-parse --is-inside-git-dir 2>/dev/null)" ]; then
            if [ "true" = "$(git rev-parse --is-bare-repository 2>/dev/null)" ]; then
                c="BARE:"
            else
                b="GIT_DIR!"
            fi
        elif [ "true" = "$(git rev-parse --is-inside-work-tree 2>/dev/null)" ]; then
            if [ -n "${GIT_PS1_SHOWDIRTYSTATE-}" ] &&
               [ "$(git config --bool bash.showDirtyState)" != "false" ]
            then
                git diff --no-ext-diff --quiet --exit-code || w="*"
                if git rev-parse --quiet --verify HEAD >/dev/null; then
                    git diff-index --cached --quiet HEAD -- || i="+"
                else
                    i="#"
                fi
            fi
            if [ -n "${GIT_PS1_SHOWSTASHSTATE-}" ]; then
                git rev-parse --verify refs/stash >/dev/null 2>&1 && s="$"
            fi

            if [ -n "${GIT_PS1_SHOWUNTRACKEDFILES-}" ] &&
               [ "$(git config --bool bash.showUntrackedFiles)" != "false" ] &&
               [ -n "$(git ls-files --others --exclude-standard)" ]
            then
                u="%"
            fi

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

        local f="$w$i$s$u"
        if [ $pcmode = yes ]; then
            local gitstring=
            if [ -n "${GIT_PS1_SHOWCOLORHINTS-}" ]; then
                local c_red='\e[31m'
                local c_green='\e[32m'
                local c_lblue='\e[1;34m'
                local c_clear='\e[0m'
                local bad_color=$c_red
                local ok_color=$c_green
                local branch_color="$c_clear"
                local flags_color="$c_lblue"
                local branchstring="$c${b##refs/heads/}"

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

                # Setting gitstring directly with \[ and \] around colors
                # is necessary to prevent wrapping issues!
                gitstring="\[$branch_color\]$branchstring\[$c_clear\]"

                if [ -n "$w$i$s$u$r$p" ]; then
                    gitstring="$gitstring "
                fi
                if [ "$w" = "*" ]; then
                    gitstring="$gitstring\[$bad_color\]$w"
                fi
                if [ -n "$i" ]; then
                    gitstring="$gitstring\[$ok_color\]$i"
                fi
                if [ -n "$s" ]; then
                    gitstring="$gitstring\[$flags_color\]$s"
                fi
                if [ -n "$u" ]; then
                    gitstring="$gitstring\[$bad_color\]$u"
                fi
                gitstring="$gitstring\[$c_clear\]$r$p"
            else
                gitstring="$c${b##refs/heads/}${f:+ $f}$r$p"
            fi
            gitstring=$(printf -- "$printf_format" "$gitstring")
            PS1="$ps1pc_start$gitstring$ps1pc_end"
        else
            # NO color option unless in PROMPT_COMMAND mode
            printf -- "$printf_format" "$c${b##refs/heads/}${f:+ $f}$r$p"
        fi
    fi
}

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.