set -euo pipefail
export LC_ALL=C
grep_work=$(mktemp -d "${TMPDIR:-/tmp}/grep-example.XXXXXX")
trap 'rm -rf -- "$grep_work"' EXIT
cd "$grep_work"
mkdir -p data
: > data/none.txt
cat > data/colors.txt <<'GRP_INPUT_2'
blue
Blue
blueberry
sky blue
red
GRP_INPUT_2

status=0
grep -Ff data/none.txt data/colors.txt || status=$?
printf 'exit=%s\n' "$status"