Power Status (was Re: Because LC can't do two things at once.)

[Michael Doub]

Looking around in /proc I found no acpi on the Pi.

-= Mike


On 3/2/15 10:30 AM, Richard Gaskin wrote:
> Peter M. Brigham wrote:
>
> > On Mar 1, 2015, at 3:16 PM, Richard Gaskin wrote:
>
> >> Thanks to the beautiful simplicity of the Linux /proc directory
> >> I was able to find:
> >>
> >>    cat /proc/acpi/battery/BAT1/state
> >>
> >> The "charging state" field there will contain "charging" or
> >> "discharging".
> >
> > Question: this looks like a file on disk. I didn't know what you
> > meant by the "'charging state' field." What is the format of the
> > file? Is this a text file, an XML file, or something else?
>
> One of the guiding design principles of Unix is "everything is a 
> file", which allows us to access not only those byte streams that are 
> actual files, but also system and process info such as that commonly 
> mounted at /proc, all with the same common tools (cd, ls, cat, grep, 
> more, less, etc.) - this page explains it well:
> <http://en.wikipedia.org/wiki/Everything_is_a_file>
>
> Being a certified Unix OS X probably has a /proc, but some Unix 
> flavors don't mount it; most Linux distros do.
>
>
> > If you could give me a sample to look at I can parse it to get
> > the info and complete the handler. I don't have a linux system
> > to work with for this.
>
> In my brief searching on this there were two files commonly noted, the 
> one shown above and also /BAT0/state.  I'm not exactly sure why my 
> laptop has a BAT1 but not a BAT0, and I'll see what I can turn up.
>
> That said, given the increasing role of servers in our connected 
> world, I can't say enough encouraging things about putting together a 
> VM with Linux in it.  Tons of fun, very educational, and you can't 
> beat the price.
>
> And if you're a history buff, there's a version of Debian with 
> OpenStep pre-installed so you can explore the look-and-feel of NeXT. :)
>
>
> Michael Doub wrote:
> > I don't know if this helps since the only linux system i have is a
> > raspberryPi, but I get a file not found message when typing cat
> > /proc/acpi/battery/BAT1/state in a terminal window.
>
> Thanks for trying that, Michael.
>
> It may be helpful to also check for BAT0, but it may also be that 
> because the Pi doesn't ship with a battery that's not normally part of 
> the info the system provides.
>
> While battery packs are available for Pi*, the device itself doesn't 
> distinguish it from running on a wall socket; it's not integrated with 
> battery monitoring firmware like laptops are.
>
> If that hunch is correct, the absence of a battery info element in 
> /proc may be an accurate reflection of the system state.
>
> I'll do some more digging and see what I can find....
>
>
>
> * I've been looking for a Pi case with an integrated battery pack.  
> I've seen several battery packs as separate cases, but I'd really 
> prefer everything in one box.  Anyone here seen one?
>