[arch-general] Automatically stop systemd service

[Leonid Isaev]

On Fri, 29 Mar 2013 01:48:55 +1100
Robbie Smith <zoqaeski at gmail.com> wrote:

> On 29/03/13 00:39, Leonid Isaev wrote:
> > On Thu, 28 Mar 2013 18:23:03 +1100
> > Robbie Smith <zoqaeski at gmail.com> wrote:
> >
> >> TL;DR: More toying with mobile broadband and systemd; would like help
> >> automatically stopping service depending on device availability.
> >>
> >> [...]
> >>
> >> What I cannot figure out how to do is automatically stop the service if
> >> the device is unplugged, similar to how ifplugd works for wired ethernet
> >> interfaces.
> >
> > How about "BindsTo=" from man 5 systemd.unit? For example,
> > "BindsTo=sys-subsystem-net-devices-wap.device".
> >
> That did the trick (when the device is /dev/ttyUSB0). Now to just make a 
> persistent name for the rare occasions when it appears as something else 
> (always a /dev/ttyUSBx).

Glad to help :)

Regarding the persistend device names, you'll have to place a udev rule
in /etc/udev/rules.d/, e.g. (there is also an archwiki page on this)
---
/etc/udev/rules.d/20-nic.rules
SUBSYSTEM=="net", ATTR{address}=="<MAC>", NAME="wan"
---
Although this is for a network card (I have never seen a 3g/4g modem). You'll
have to run something like "udevadm info --path=/sys/class/net/wan
--attribute-walk" replacing 'wan' with your device name to find persistent
attributes.

L.

-- 
Leonid Isaev
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