Re: open SHM data only after cgps start

[Frank Nicholas]

I think you have two issues:
1. Dirty system with multiple installations of various versions of GPSd
2. You are using SystemD, which with the most common service file, only 
launched GPSd when an app/client attempts to attach.  As long as GPSd is 
launched, and there is an attached client/consumer, it will continue to run, 
until there is nothing else using it and the last client closes the connection.

Gary Miller suggested adding the switch to make GPSd run as a daemon all the 
time (doesn’t exit when there are no clients attached).  This would also 
require something to change with the SystemD config file - you want SystemD to 
start GPSd at boot, not wait until there’s a client attempting to access it.  I 
think Gary even provided a one line command line that could be put in a startup 
script, anywhere you wanted, depending on the flavor of Linux you are using 
(this would not use SystemD).

For some reason all your messages are coming individually - not recognized as 
part of a discussion/thread.  Not sure if you can do something about that, but 
it makes it difficult to follow - that’s why I couldn’t easily find Gary’s 
suggestions.

Thanks,
Frank

> On Feb 5, 2021, at 8:59 AM, Hans Kurscheidt <lve0200@gmail.com> wrote:
> 
> Sorry, if I keep talking to myself here, but I'm crawling forward.
> 
> After I got gpsd running as service, I cleaned out all old references to 
> libgps and libgps-dev and cleaned Visual Studio's cache.
> 
> Should be OK now.
> 
> There's no dpkg -l libgps* output anymore
> 
> VisualStudio finds the richgt gps.h under ../gpsd-master/..; there is no 
> other gps.h somewhere.
> 
> and the linker points to so.28
> 
> ldconfig -p | grep gps
>         libgpsdpacket.so.28 (libc6,hard-float) => 
> /usr/local/lib/libgpsdpacket.so.28
>         libgpsdpacket.so (libc6,hard-float) => /usr/local/lib/libgpsdpacket.so
>         libgps.so.28 (libc6,hard-float) => /usr/local/lib/libgps.so.28
>         libgps.so (libc6,hard-float) => /usr/local/lib/libgps.so
>         libQgpsmm.so.28 (libc6,hard-float) => /usr/local/lib/libQgpsmm.so.28
>         libQgpsmm.so (libc6,hard-float) => /usr/local/lib/libQgpsmm.so
> 
> The compilation/linking is OK w/out errors or warnings and the executable is 
> runable
> 
> BUT, I still have the old problem. (assume gpsd service running and fix 
> available)
> 
> If I run my app after boot, No gps data is available and just once I got an 
> error message, which I cannot reproduce, saying something like:
> 
> shared library error cannot ... data: No such file or directory
> 
> After running cgps once, data is available and remains 2b supplied to my app, 
> even if I close cgps. This is reproduceable.
> 
> RGDS
> 
> hk
> 
>