color_bash_prompt.sh

# fails to properly return true when running sudo -s
function is_ssh_from_env() {
  if [ -n "${SSH_TTY}" ] || \
     [ -n "${SSH_CONNECTION}" ] || \
     [ -n "${SSH_CLIENT}" ]; then
    echo "true"
  else
    echo "false"
  fi
}
 
# fails to properly return true using xterm
function is_ssh_from_who() {
  # method doesn't work in an xterm so just return false
  if [ -n "${XTERM_SHELL}" ]; then
    echo "false"
    return
  fi
 
  if [[ $(who -m) =~ \([-:a-zA-Z0-9\.]+\)$ ]]; then
    echo "true"
  else
    echo "false"
  fi
}
 
# fails to return true when not running from linux or when connected to a
# screen not started under ssh
function is_ssh_from_ppid() {
  # only works with /proc directory. otherwise return false
  p=${1:-$PPID}
  if [ -f /proc/$p/stat ]; then
    read pid name x ppid y < <( cat /proc/$p/stat )
    [[ "$name" =~ sshd ]] && { echo "true"; return; }
    [ "$ppid" -le 1 ] && { echo "false"; return; }
    is_ssh_from_ppid $ppid
  else
    echo "false"
  fi
}
 
# not totally reliable but works in a lot of cases (may not work in xterms)
# also the functions it relies on don't return any known false positives,
# only false negatives
function is_ssh() {
  if "$(is_ssh_from_env)" || \
     "$(is_ssh_from_who)" || \
     "$(is_ssh_from_ppid)"; then
    echo "true"
  else
    echo "false"
  fi
}
 
function is_xterm() {
  if [ -n "${XTERM_SHELL}" ] || \
     [ -n "${XTERM_LOCALE}" ] || \
     [ -n "${XTERM_VERSION}" ]; then
    echo "true"
  else
    echo "false"
  fi
}

# root prompt red (even in ssh session since if you sudo -s in an ssh session
# there seemingly isn't a way to know you're in an ssh session)
if [ "root" == "$(whoami)" ]; then
  USER_COLOR="31m"
else
  USER_COLOR="32m"
fi

# if you're running in an xterm, you can't reliably determine remote status,
# so just use default color
if "$(is_xterm)"; then
  HOST_COLOR="0m"
elif "$(is_ssh)"; then
  HOST_COLOR="36m"
else
  HOST_COLOR="34m"
fi
 
PS1="\n\[\e[${USER_COLOR}\]\u\[\e[0m\]@\[\e[${HOST_COLOR}\]\h "
PS1+="\[\e[33m\]\w\[\e[0m\]\n\$ "