rm(u)mount don't always print mount/unmount errors
The rmmount or rmumount commands print out an error message unless the device they're trying to mount/unmount is already mounted/unmounted. An exit status of 1 is always returned on error.
Updated by Andrew Stormont about 6 years ago
Example errors now displayed after changset:
mount of /dev/dsk/c3t0d0s2 failed: Device /dev/dsk/c3t0d0s2 is already mounted.
unmount of /dev/dsk/c3t0d0s2 failed: According to HAL, the volume is not mounted
No mountable partition on disk:
no volumes on '/dev/dsk/c3t0d0s2' to mount
No disc in drive:
no volumes in 'cdrom' to mount