Here are two quick and dirty ways of checking the duplex setting of all interfaces as a non-root user:
kstat -p | grep link_duplex | grep mac |
0=link down 1=half duplex 2=full duplex
Or
ndd /dev/hme link_status ndd /dev/hme link_mode ndd /dev/hme link_speed |
link_status: 0=down 1=up
link_mode: 0=half 1=full
link_speed: 0=10 1=100
