-[ -n "$COLORTERM" ] && PS1_COLOR=1
-[ "$TERM" = "linux" ] && PS1_COLOR=1 && DARK=1
-[ "$TERM" = "screen" ] && PS1_COLOR=1
-[ "$TERM" = "xterm" ] && PS1_COLOR=1
-[ "$TERM" = "xterm-color" ] && PS1_COLOR=1
-[ "$TERM" = "rxvt" ] && PS1_COLOR=1
-[ "$TERM" = "rxvt-unicode" ] && PS1_COLOR=1
+[ -n "${COLORTERM}" ] && PS1_COLOR=1
+[ "${TERM}" = "linux" ] && PS1_COLOR=1 && DARK=1
+[ "${TERM}" = "screen" ] && PS1_COLOR=1
+[ "${TERM}" = "xterm" ] && PS1_COLOR=1
+[ "${TERM}" = "xterm-color" ] && PS1_COLOR=1
+[ "${TERM}" = "rxvt" ] && PS1_COLOR=1
+[ "${TERM}" = "rxvt-unicode" ] && PS1_COLOR=1