Adding in check_group_membership to launch script

[rsdoiel]

I've added a simple check in the startup script to see if the logged in user is in the following groups

• weston-launch
• video
• audio

This prevents the human hostile errors of weston failing to launch properly because of security restrictions. This approach is generally debian friendly but has only be tested in the Raspberry Pi. Other Unix may use other permissions.

[jonnylamb]

I only just noticed this patch, thanks! Just two points:

Indentation seems a bit odd in places?

Is there any way we can not make this bash-specific? It seems an unnecessary addition for what the patch actually does.