$ for d in /dev/ttyd0 /dev/ttyid0 /dev/ttyld0 /dev/cuaa0; do dd if=$d bs=1 count=0; done (as uid=1001)
open /dev/ttyd0:  dd: Permission denied
open /dev/ttyid0: dd: Permission denied
open /dev/ttyld0: dd: Permission denied
open /dev/cuaa0:  dd: Permission denied
uid=1001(maxx) gid=1001(maxx) groups=1001(maxx)