basic errorcode enabled bash prompt

gistfile1.sh

#for ~/.bashrc
DULL=0
FG_RED=31
FG_GREEN=32
ESC="\033"
NORMAL="\[$ESC[m\]"
RED="\[$ESC[${DULL};${FG_RED}m\]"
GREEN="\[$ESC[${DULL};${FG_GREEN}m\]"
PS1="$NORMAL \$(if [[ \$? == 0 ]]; then echo \"$GREEN\342\234\223\"; else echo \"$RED\342\234\227\"=\$?; fi) $NORMAL\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w \$ "

looks like: (but with green ✓ and red ✗=)

 ✓ user@host:~ $ true
 ✓ user@host:~ $ false
 ✗=1 user@host:~ $ 
 ✗=1 user@host:~ $ true
 ✓ user@host:~ $