beadm(1M): beadm mount should list mountpoint argument as optional
beadm mount [-s ro|rw] [-v] beName mountpoint Mounts a boot environment named beName at mountpoint. mountpoint must be an already existing empty directory.
That isn't quite correct, mountpoint argument is optional, and if it's omitted, tmp directory is created.
Updated by Damian Wojslaw about 5 years ago
Yuri's comment on illumos devel:
_We could be more verbose on how mountpoint name is generated:
If mountpoint is not specified, beadm uses environment variable TMPDIR, or "/tmp" if TMPDIR isn't set, as a prefix and "tmp.XXXXXX" as a template to make unique mountpoint name where BE will be mounted (see mkdtemp(3C)).
And add a description of TMPDIR to ENVIRONMENT VARIABLES section as well._
Will work on it.