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

[Richard Purdie]

On Tue, 2018-05-29 at 12:41 +0200, Arno Steffens wrote:
> 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

You have one reply/potential solution. Another option is to set udev
rules (or the equivalent in systemd) such that when the device files
are created they get the permissions/ownership you need.

Cheers,

Richard