[poky] Give others users than "root" access to GPIO (or commands)

[Arno Steffens]

I have to add a user other than root to start a program which operates with i2c, spi, gpio.
For this I added an init-script /etc/rc5.d to make it /dev/* r/w for "others".
That works for i2c and spi but not for GPIO. As most of the files the user has to access will only created after the exporting the GPIOs (more or less doing echo xxx > /sys/class/gpio/export).
But this new created /sys/class/gpio/xxx is not writable by user.

Maybe I am doing it completely wrong, but how can I achieve this to become possible?
I checked the mega-manual, but there is not much mentioned about groups (27.36. extrausers.bbclass).
Best regards
Arno

Maybe I also have to give this user the permission to reboot, which is right now only possible for root