Which boot environment is currently booted?

D
man beadm
beadm list [-a | -ds] [-H] [beName]

Lists information about the existing boot environment
named beName, or lists information for all boot environ-
ments if beName is not provided. The Active field indi-
cates whether the boot environment is active now,
represented by N; active on reboot, represented by R; or
both, represented by NR. Unbootable BEs inside of a
nested BE are represented by an exclamation point (!)