dot_bash_prompt

#!/usr/bin/env bash
#
# DESCRIPTION:
#
#   Set the bash prompt according to:
#    * the active virtualenv
#    * the branch of the current git/mercurial repository
#    * the return value of the previous command
#
# USAGE:
#
#   1. Save this file as ~/.bash_prompt
#   2. Add the following line to the end of your ~/.bashrc or ~/.bash_profile:
#        . ~/.bash_prompt
#
# LINEAGE:
#
#   Based on work by woods
#
#   https://gist.github.com/31967

# shellcheck disable=SC2034
# The various escape codes that we can use to color our prompt.
BLACK="\[\033[0;30m\]"
LIGHT_BLACK="\[\033[1;30m\]"
RED="\[\033[0;31m\]"
LIGHT_RED="\[\033[1;31m\]"
GREEN="\[\033[0;32m\]"
LIGHT_GREEN="\[\033[1;32m\]"
YELLOW="\[\033[0;33m\]"
LIGHT_YELLOW="\[\033[1;33m\]"
BLUE="\[\033[0;34m\]"
LIGHT_BLUE="\[\033[1;34m\]"
PURPLE="\[\033[0;35m\]"
LIGHT_PURPLE="\[\033[1;35m\]"
CYAN="\[\033[0;36m\]"
LIGHT_CYAN="\[\033[1;36m\]"
WHITE="\[\033[0;37m\]"
LIGHT_WHITE="\[\033[1;37m\]"
COLOR_NONE="\[\e[0m\]"

function swatch() {
  echo "black${BLACK}black${COLOR_NONE}"
  echo "light black${LIGHT_BLACK}light black${COLOR_NONE}"
  echo "red${RED}red${COLOR_NONE}"
  echo "light red${LIGHT_RED}light red${COLOR_NONE}"
  echo "green${GREEN}green${COLOR_NONE}"
  echo "light green${LIGHT_GREEN}light green${COLOR_NONE}"
  echo "yellow${YELLOW}yellow${COLOR_NONE}"
  echo "light yellow${LIGHT_YELLOW}light yellow${COLOR_NONE}"
  echo "blue${BLUE}blue${COLOR_NONE}"
  echo "light blue${LIGHT_BLUE}light blue${COLOR_NONE}"
  echo "purple${PURPLE}purple${COLOR_NONE}"
  echo "light purple${LIGHT_PURPLE}light purple${COLOR_NONE}"
  echo "cyan${CYAN}cyan${COLOR_NONE}"
  echo "light cyan${LIGHT_CYAN}light cyan${COLOR_NONE}"
  echo "white${WHITE}white${COLOR_NONE}"
  echo "light white${LIGHT_WHITE}light white${COLOR_NONE}"
}

# Determine branch name and dirty state for the current git repository in a
# single `git status` call.
function set_git_branch() {
  local status_output line branch="" dirty=""
  status_output=$(command git status --porcelain=v2 --branch \
    --untracked-files=no --ignore-submodules 2>/dev/null) || {
    BRANCH=""
    return
  }
  while IFS= read -r line; do
    case $line in
    "# branch.head "*)
      branch=${line#"# branch.head "}
      [ "$branch" = "(detached)" ] && branch="detached"
      ;;
    "#"*) ;;
    ?*) dirty=" *" ;;
    esac
  done <<<"$status_output"
  BRANCH="${RED}(${branch})${LIGHT_RED}${dirty}${COLOR_NONE} "
}

# Determine the kubectl context/namespace, but only when a kubeconfig exists.
function set_k8s_prompt() {
  K8S=""
  [ -n "${KUBECONFIG}" ] || [ -f "${HOME}/.kube/config" ] || return
  command -v kubectl >/dev/null 2>&1 || return
  local kube context namespace
  kube=$(command kubectl config view --minify \
    -o "jsonpath={.current-context}|{.contexts[0].context.namespace}" 2>/dev/null) || return
  context=${kube%%|*}
  namespace=${kube#*|}
  [ -n "${context}" ] || return
  if [ -n "${namespace}" ]; then
    K8S="${LIGHT_GREEN}${context}${WHITE}|${GREEN}${namespace}${COLOR_NONE} "
  else
    K8S="${LIGHT_GREEN}${context}${COLOR_NONE} "
  fi
}

# Return the prompt symbol to use, colorized based on the return value of the
# previous command.
function set_prompt_symbol() {
  if test "$(id -u)" -eq 0; then
    SYM="#"
  else
    SYM="\$"
  fi
  if test "$1" -eq 0; then
    PROMPT_SYMBOL="${SYM}"
  else
    PROMPT_SYMBOL="${LIGHT_RED}$1 ${SYM}${COLOR_NONE}"
  fi
}

# Determine active Python virtualenv details.
function set_virtualenv() {
  if test -z "$VIRTUAL_ENV"; then
    PYTHON_VIRTUALENV=""
  else
    PYTHON_VIRTUALENV="${LIGHT_WHITE}[$(basename "$VIRTUAL_ENV")]${COLOR_NONE} "
  fi
}

function set_date_prompt() {
  DATE_PROMPT="${WHITE}$(date +'%H:%M:%S')${COLOR_NONE} "
}

# Set the full bash prompt.
if command -v bashline >/dev/null 2>&1; then
  set_bash_prompt() {
    PS1='$(bashline --exit-code=$? --shlvl=$SHLVL --jobs=\j)'
  }
else
  set_bash_prompt() {
    # Set the PROMPT_SYMBOL variable. We do this first so we don't lose the
    # return value of the last command.
    set_prompt_symbol $?

    # Set the PYTHON_VIRTUALENV variable.
    set_virtualenv

    # Set the BRANCH variable.
    set_git_branch

    # set k8s prompt
    set_k8s_prompt

    # set date string
    set_date_prompt

    USERLINE="${CYAN}\u@${LIGHT_CYAN}\h${COLOR_NONE}:${LIGHT_YELLOW}\w${COLOR_NONE} "

    # Set the bash prompt variable.
    PS1="
${PYTHON_VIRTUALENV}${USERLINE}${BRANCH}${K8S}
${DATE_PROMPT}${PROMPT_SYMBOL} "
  }
fi

# Tell bash to execute this function just before displaying its prompt.
PROMPT_COMMAND=set_bash_prompt