gdm registers its login screen as a session because it *is* in essence a regular (if trimmed down) GNOME session. It follows the same logind rules for accessing the display, audio out, etc. Various desktop services and recently even programs use DBus activation – instead of launching them directly, the consumer app tells DBus to start them (either explicitly or just by trying to talk to the activatable service). So usually you'd see quite a few processes as children of dbus-daemon. * If your distro has switched to the "user bus" model, then dbus-daemon will be running as a systemd --user service, and therefore under user@. * In addition to that, some apps have their own systemd --user services, and DBus uses those to start the app. <div class="gmail_quote"><div dir="ltr">On Tue, May 23, 2017, 12:12 Олег Гаврильченко <<a href="mailto:Gavrilchenko@avionica.spb.ru">Gavrilchenko@avionica.spb.ru</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="RU" link="#0563C1" vlink="#954F72"><div class="m_548725605519889933WordSection1"> <div><div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0cm 0cm 0cm">From: Олег Гаврильченко [mailto:<a href="mailto:Gavrilchenko@avionica.spb.ru" target="_blank">Gavrilchenko@avionica.spb.ru</a>] Sent: Monday, May 22, 2017 6:17 PM To: '<a href="mailto:systemd-devel@lists.freedesktop.org" target="_blank">systemd-devel@lists.freedesktop.org</a>' <<a href="mailto:systemd-devel@lists.freedesktop.org" target="_blank">systemd-devel@lists.freedesktop.org</a>> Subject: Question about systemd sessions</div></div> Hello!I have question about systemd user sessions.When I start my systemd system and login to it I see 2 user sessions: c1 for user gdm and c2 for my user. I see 2 (<a href="mailto:user@120.slice" target="_blank">user@120.slice</a> and <a href="mailto:user@1000.slice" target="_blank">user@1000.slice</a>) slices and 2 scopes(session-c1.scope and session-c2.scope). Several programs or deamons reside in <a href="mailto:user@.slice" target="_blank">user@.slice</a>, other in session-c*.scope. I don't understend and can not find in documentation, why is there 2 and not 1 session in system? And why does several programs reside in <a href="mailto:user@.slice" target="_blank">user@.slice</a> and other in session-c*.scope?</div></div>_______________________________________________ systemd-devel mailing list <a href="mailto:systemd-devel@lists.freedesktop.org" target="_blank">systemd-devel@lists.freedesktop.org</a> <a href="https://lists.freedesktop.org/mailman/listinfo/systemd-devel" rel="noreferrer" target="_blank">https://lists.freedesktop.org/mailman/listinfo/systemd-devel</a> </blockquote></div><div dir="ltr">-- </div><div data-smartmail="gmail_signature">Mantas Mikulėnas <<a href="mailto:grawity@gmail.com">grawity@gmail.com</a>> Sent from my phone </div>