Re: How to set default screen brightness?

[Jesse Gibbons]

On Sat, 15 Jun 2019 19:41:13 +0200
Tobias Geerinckx-Rice <address@hidden> wrote:

> Jesse,
> 
> Jesse Gibbons wrote:
> > My Librem 13 laptop battery lasts much longer with a lower 
> > screen
> > brightness. When it runs gnome on guix (and I haven't tried any 
> > other
> > de) I have to turn down the brightness every time. This is not 
> > so with
> > my other partition running PureOS. Is there a way to configure a
> > default screen brightness in guix/gnome?  
> 
> Guix doesn't have a notion of ‘default’ screen brightness because 
> it doesn't know anything about brightness.
> 
> My guess is that PureOS uses systemd; systemd provides a 
> backlight.service that reads the backlight brightness at shutdown, 
> stores it to disc, and writes that value back to the device at 
> next start-up.
> 
> It would be a relatively trivial service to add, but that hasn't 
> been done yet :-)
> 
> We do already provide a simple, script-friendly abstraction tool¹:
> 
>   $ guix install light
>   $ sudo light -S 50 # percentage
> 
> It can even run setuid.
> 
> Kind regards,
> 
> T G-R
> 
> [1]: As opposed to manually reading and writing `find /sys -path 
> *backlight*brightness*`.

Thanks. I think I can add a service using the `light` tool.
Administrators will likely prefer to install it on anything with a
display that runs on battery power, so I might contribute it in
gnu/services/pm.scm if nobody beats me to it.
-Jesse