How to list user services of another user under ubuntu

Question

There is the usual command for listing the systemd services:

systemctl list-units --type=service

Then there is the --user parameter for enabling and starting a user service, executing the command from a user's session:

systemctl --user enable/start <service name>

I need, as root, to list services running under a certain user, something like:

systemctl list-units --type=service --user <username>

Haven't been able to find anything about this. Is it even possible?

Answer 1

Yes, it is, but by using sudo. Read man sudo sudoers, and

sudo -u theuser systemctl ...

will do the trick.

Answer 2

Use the machinectl command like this:

machinectl shell <username>@ /usr/bin/systemctl --user list-units --type=service --quiet

Here is an example with the local account erikdev on my computer.

[root@laptop ~]# machinectl shell erikdev@ /usr/bin/systemctl --user list-units --type=service --quiet
Connected to the local host. Press ^] three times within 1s to exit session.
  systemd-tmpfiles-setup.service loaded active exited Create User's Volatile Files and Directories

Connection to the local host terminated.
[root@laptop ~]# 

I'm running Systemd 248 on a Fedora 34 Linux computer.

[root@laptop ~]# cat /etc/fedora-release 
Fedora release 34 (Thirty Four)
[root@laptop ~]# machinectl --version
systemd 248 (v248.3-1.fc34)
+PAM +AUDIT +SELINUX -APPARMOR +IMA +SMACK +SECCOMP +GCRYPT +GNUTLS +OPENSSL +ACL +BLKID +CURL +ELFUTILS +FIDO2 +IDN2 -IDN +IPTC +KMOD +LIBCRYPTSETUP +LIBFDISK +PCRE2 +PWQUALITY +P11KIT +QRENCODE +BZIP2 +LZ4 +XZ +ZLIB +ZSTD +XKBCOMMON +UTMP +SYSVINIT default-hierarchy=unified
[root@laptop ~]# 

It might be possible to use systemd-run instead of machinectl, but I didn't get that to work.