shell/ash_test/ash-quoting/negative_arith.tests

>tempfile0.tmp
>tempfile1.tmp
>tempfile9.tmp
# The [...] is interpreted as: "any of the chars 0, -, and 9"
echo tempfile[0"$((-9))"].tmp
# The [...] is [0-9], interpreted as: "any digit"
echo tempfile[0$((-9))].tmp
rm tempfile?.tmp