[LAU] systemd woes with jackd and its permissions (raspbian)

Len Ovens len at ovenwerks.net
Mon Jan 28 01:59:07 CET 2019

On Mon, 28 Jan 2019, Peter P. wrote:

> Now I try to start jackd automatically from a systemd service file
> created as /etc/systemd/system/jackd.service with the following

why /etc/systemd/system and not /etc/systemd/user/?

> contents:
> 	[Unit]
> 	Description=jackd
> 	After=sound.target
> 	[Service]
> 	User=peter

Does systemd allow Group=audio

> 	ExecStart=/usr/bin/jackd -d alsa -r 44100 -P

Would it be better starting a bash -l -c to wrap jackd?

You seem to be wanting to run this before any user is logged in. Does that 
mean the user will run automatically or unattended? If so, I would use a 
multi-terminal text session manager like screen which can start itself 
with a number of processes running. If started by dbus-launch, you would 
still have that functionality as well. hmm, I am thinking about this and 
realizing I have not tried this trick with systemd, but /etc/rc.local 
(which should still work with systemd).

OK, from:
would start things as group audio and may have trouble writing logs etc. 
to the user directorys.
starting the commandline with + has some effect on this but if that opens 
things or restricts them I am not sure.
SupplementaryGroups=audio may give both group=user and group=audio
Systemd should be set up for security and as such default to a lower 
security level rather than higher. So even though the user is a part of 
more than one group, the actual groups needed by the process may need to 
all listed.

Len Ovens

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