Ok, thanks! As always it is not as easy as thought but it works, I get "Linux Arduino 3.3.8 #1 Fri Nov 14 08:57:34 CET 2014 mips GNU/Linux". I was confused about 1.5.3 vs. 3.3.8 and OpenWrt-Yun vs. Linux Arduino vs. Arduino Yun Linux OS (last two the same?).