Re: systemd/udev/hotplug installation on Ubuntu 19.10

[John Ackermann N8UR]

On 5/1/20 2:12 PM, Gary E. Miller wrote:
> Yo John!
> 
> On Fri, 1 May 2020 10:47:03 -0400
> John Ackermann N8UR <address@hidden> wrote:
> 
>> Just built gpsd from head.  Trying to get the udev hotplug stuff
>> working, ultimately for multiple receivers, but for now just one would
>> be nice.
> 
> IN general not a good idea.

I'll take your word for that and stop worrying hotplug -- I don't really
need it, but it appeared from the installation instructions that it
ought to work, so I thought I'd give it a try.  I won't waste a lot more
time on it.

>> Following the troubleshooting guide, I tried "make udev-install" and
>> no target was found.  So I did "sudo scons udev-install" which did
>> install the udev rules in /lib/udev/rules.d
> 
> sudo is bad for you.  You should already know that all installs and
> system configuration needs root.  

I actually don't know that.  This is the first time I've ever
encountered or heard of it as a problem.  Virtually all the software
I've built from github or elsewhere tells you to build unprivileged, and
then install with sudo make install or whatever.

By default, Ubuntu doesn't allow direct login as root, or su to root.
The only way to get anything like root is "sudo -i" so there's no way
*not* to use sudo. :-)  See https://help.ubuntu.com/community/RootSudo


~~~~

I just rebuilt using sudo -i (closest I can get to root per above) to
get a root shell and did exactly this line from build.adoc:

scons && scons check && sudo scons udev-install

NOTE: that "sudo" was in build.adoc so the documentation conflicts with
your statement above... but if I were running the build process as an
unprivileged user, it's exactly what I would expect to see in the
instructions for the install step.  I'm not sure what it accomplishes if
you're already root.

~~~~

So after all that:

Now, when a device is plugged the kernel reports that it is detected and
a device (/dev/ttyACM0) has been assigned.  But that's usually the last
related message.

Sometimes, I'll get this line in /var/log/syslog:

    May  1 10:04:10 lintty gpsd.hotplug: no device

but I think that happens only once per reboot; unplugging and replugging
doesn't generate a new line.

So it still doesn't work.

I'm not going to spend any more time on this if hotplug is generally
considered a bad idea anyway.

John