I woud like to know where to find power usage info myself. (Been using unix shells for over 20 years.)
The lshal -command gives one item that is battery.charge_level.percentage. I wrote a quick shell script for fetching just the percentage from it:
lshal | grep battery.charge_level.percentage | awk '{print $3}'
I put it in /usr/bin/bat using vi and chmodded it 755. Now I can write "bat" anywhere in the terminal and get the batterylevel.
Too bad it only works when your device is not charging. When it's connected to a charger it shows 0.