shell - How do I view/mount nandroid file on device?

From Android's terminal, I tried to mount a nandroid img:

losetup -f

gives "/dev/loop0".

However, when I try losetup /dev/loop0 /sdcard/nandroid/... data.img it says no such directory. Same thing when I try to mount the file.

According to this it should be doable, but it seems there must be some trick to mounting it in Android? https://en.wikipedia.org/wiki/Loop_device