There's normally no need for ${var-} to get default values, and you can put && inside. I'd write that as: [[ -z $NO_COLOR && $TERM != dumb ]] As another c

There's normally no need for ${var-} to get default values, and you can put && inside. I'd write that as: [[ -z $NO_COLOR && $TERM != dumb ]] As another comment pointed out, they're erroring on unset values. I don't think the line noise is worth it, but it will catch spelling mistakes, I guess.