$ sudo gem install iStats
$ istats
--- CPU Stats ---
CPU temp: 48.125°C ▁▂▃▅▆▇
--- Fan Stats ---
Total fans in system: 1
Fan 0 speed: 1297.0 RPM ▁▂▃▅▆▇
--- Battery Stats ---
Battery health: Good
Cycle count: 68 ▁▂▃▅▆▇ 6.8%
Max cycle count: 1000
Current charge: 5151 mAh 86%
Maximum charge: 6269 mAh ▁▂▃▅▆▇ 99.0%
Design capacity: 6330 mAh
Battery temp: 30.8°C