Prefer `[` over `[[`
Prefer `[` over `[[`

`[` is more portable to other shells. In this script I'm using `[[` only
where it buys me something I can't conveniently do with `[` (for
example, easily testing for set-ness of the `$FORCE` variable).

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent