Using REST with Arduino Yún - The Hands-on Arduino Yun Manual Lab - page 105

6.4 Testing Analog I/O
We also can work with analog I/O. We don't need to set mode for analog I/O. For instance,
we want to read analog input A1. Navigate this URL on your browser.
http://arduino.local/arduino/analog/1
Ifyouwant to set analog output, forinstance A1,with value 258.Navigate this URL onyour
browser.
http://arduino.local/arduino/analog/1/258