1if command -v sha256sum >/dev/null; then
 2	exec sha256sum "$@"
 3elif command -v sha256 >/dev/null; then
 4	exec sha256 "$@"
 5elif command -v shasum >/dev/null; then
 6	exec shasum -a 256 "$@"
 7else
 8	printf '%s: sha256sum, sha256, or shasum required\n' "$0" >&2
 9	exit 1
10fi