I use usbmux for my iphone so I can access my photos via shotwell and move files around. I have to start the service manually via systemd. When I try to enable I get the following.
hhernandez@hhernandez-Precision-M4800:~$ sudo systemctl enable usbmuxd
[sudo] password for hhernandez:
The unit files have no installation config (WantedBy, RequiredBy, Also, Alias
settings in the [Install] section, and DefaultInstance for template units).
This means they are not meant to be enabled using systemctl.
Possible reasons for having this kind of units are:
1) A unit may be statically enabled by being symlinked from another unit's
.wants/ or .requires/ directory.
2) A unit's purpose may be to act as a helper for some other unit which has
a requirement dependency on it.
3) A unit may be started when needed via activation (socket, path, timer,
D-Bus, udev, scripted systemctl call, ...).
4) In case of template units, the unit is meant to be enabled with some
instance name specified.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: usbmuxd 1.1.0-2build1
ProcVersionSignature: Ubuntu 4.15.0-36.39-generic 4.15.18
Uname: Linux 4.15.0-36-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
CurrentDesktop: MATE
Date: Mon Oct 22 13:04:24 2018
SourcePackage: usbmuxd
UpgradeStatus: No upgrade log present (probably fresh install)
Thank you for your bug report. What iphone model do you have? The service should start when you connect your device, can you boot, log in add, connect the device and add your journalctl log then?