#
# Set the prompt based on 1st arg, which if
# invoked with $? will set it based on pass/fail
# of the previous command.
# based on work by Karl D. @ Lewis&Clark
#
promptcolor() {
    local X=32
    if [[ $1 != "0" ]]; then X=31; fi
    printf "%s" "\[\e[01;${X}m\]"
}

# bash runs this command before each prompt is printed;
# we have it redfine the prompt to set the color appropriately.
PROMPT_COMMAND='PS1="$(promptcolor $?)\u@\h\[\e[0m\]\$ ";'