unix condition checking!

Question

what condition is being checked below?

if [[ ! -s ${FILE} || -z ${FILE} ]]

(here $FILE is a data file)

Answer 1

See the manpage for test(1). $FILE either does not exist, has zero size, or is an empty string.

Answer 2

! -s ${FILE}

checks if file exists and is not empty

-z ${FILE}

checks if the FILE string length is zero