Alexander Shukaev's questions

Here is an /etc/fstab record example of one of the mounts as per x-systemd.automount and other goodies:

UUID=XXXX-XXXX /media/XXXX-XXXX auto noauto,nofail,nouser,uid=root,gid=users,umask=007,X-mount.mkdir,x-systemd.automount,x-systemd.device-timeout=1,x-systemd.idle-timeout=60 0 2

Currently this external exFAT-formatted drive is physically disconnected from the PC, but I still get the following surprises

$ ls /media
ls: cannot access '/media/XXXX-XXXX': No such device

and

$ findmnt /media/XXXX-XXXX
TARGET           SOURCE    FSTYPE OPTIONS
/media/XXXX-XXXX systemd-1 autofs rw,relatime,fd=55,pgrp=1,timeout=60,minproto=5,maxproto=5,direct,pipe_ino=24590

This obviously fools other software, which might potentially be using findmnt to determine whether the mount is up, to believe that the storage drive is actually mounted and to proceed with further actions.

How do I make sure that when the drive is physically disconnected, it is no longer considered by the Linux system?

The Type=oneshot unit A.service is started hourly by A.timer and it Wants=B.service, but runs Before=B.service. Unit B.service is also Type=oneshot. The requirement here is that their processes should never overlap at run time (oneshot ensures exactly that), all great so far. Now imagine a scenario where both A and B together run for more than an hour (time between A.timer fires). There are two possibilities here:

1. A runs more than an hour, then although A.timer wants to fire and it probably does, regardless, another instance of A will not be started until the first one finishes as service instance uniqueness is one of fundamental principles in systemd. I believe it will be merely queued. Again, all great so far, we have no risk of overlapping processes at run time here.
2. A runs long enough, so that B, which runs afterwards, also runs long enough to exceed one hour in total, and as a result, A.timer fires to start new A while B is still running. That's where we run into a process overlap because there is no After=B.service in A.service as there is already Before=B.service.

My question is, basically, whether it is valid to even have both After=B.service and Before=B.service in A.service in the first place? And, of course, would it resolve the overlapping issue described in the second possibility as I theoretically expect? Is there any other systemd-way to solve this issue (e.g. I don't want to get involved with error-prone lock file bloat)?

I want Dante to transparently choose between either of the two interfaces enp4s0 (Wired Ethernet) and wlp3s0 (Wi-Fi) regardless of their status (up or down). That is

• when wired, it should choose enp4s0 indeed,
• when wlp3s0 is added, it should preferably stay on enp4s0 (or maybe do some other clever stuff, I care less about this point here),
• when wire (enp4s0) is down, i.e. I'm traveling, it should of course switch to wlp3s0 as the only option left.

Now I was under impression that the following configuration should do the trick:

internal: 0.0.0.0 port=1080
external: enp4s0
external: wlp3s0
external.rotation: route

However, to my surprise, when e.g. only enp4s0 is up and wlp3s0 is down, Dante refuses to start up, barking:

error: /etc/sockd.conf: problem on line ??? near token "wlp3s0": could not resolve hostname "wlp3s0": No address associated with hostname.  Please see the Dante manual for more information

I do understand the point here, but there is no technical reason behind such limitation. Manually editing this configuration file every time I'm switching between wire and Wi-Fi would be cumbersome and a big no-no. Is there a clever way to address that issue?

As the last resort, maybe some hook script that would modify the configuration file? Examples of such tools/scripts?