I am trying to run systemctl from a script to enable some systemd user session services inside a sysroot which is going to be used by an embedded system later.

I found out, though, that when I run systemctl with both --global (to specify I want to enable a user systemd service) and --root (to specify the sysroot of the target system) parameters, I just get an error. For instance, it can easily be checked like this:

# systemctl --global enable myapp.service
ln -s '/usr/lib/systemd/user/myapp.service' '/etc/systemd/user/default.target.wants/myapp.service'

# systemctl --global --root=/ enable myapp.service
Operation failed: Invalid argument


Is that a bug or an expected behavior? how should I accomplish what I want to do if that's expected?


More information:
~# systemctl --version
systemd 211
+PAM +LIBWRAP -AUDIT -SELINUX +IMA +SYSVINIT -LIBCRYPTSETUP -GCRYPT +ACL +XZ -SECCOMP -APPARMOR