Welcome to rs-dos!

This file lives on the FAT32 data disk (the one mounted at /disk).
The kernel mounts the first valid FAT32 volume it finds — create or
re-seed this image with:

    make disk            # create if missing (default /tmp/disk.img)
    make disk-fresh      # re-format + re-seed from seed/

Everything written from the shell survives reboots: it's a real disk,
not RAM.