It's an ioctl, so, no idea if anyone ever tried to handle ioctls in shell

.
EDIT³: You might be able to go through sysfs though (at least on *some* devices, f.g, /sys/class/backlight/mxc_msp430.0/brightness on Mk.7).
EDIT: Speaking of the fl & ntx_io. (Missed a new page, yet again

).
EDIT²: Fun fact: on the Forma, while the gsensor is still accessible @ event2, you only get raw X/Y/Z coords from there. The computed "misc" rotation events have moved to the ntx events @ event0.