/usr/lib/os-probes/mounted/80minix is in os-prober 1.65+deb8u1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | #!/bin/sh
set -e
. /usr/share/os-prober/common.sh
partition="$1"
dir="$2"
type="$3"
# Weed out stuff that doesn't apply to us
case "$type" in
	minix|minix2|ext2) ;;
	*) exit 1 ;;
esac
if [ -f "$dir/minix" ] || [ -e "$dir/boot/image_big" ]; then
	if [ -e "$dir/boot/image_latest" ]; then
		boot="minix"
	else
		boot="chain"
	fi
	label="$(count_next_label Minix)"
	result "$partition:Minix:$label:$boot"
	exit 0
else
	exit 1
fi
 |