$ loginctl show-session c2
Id=c2
Name=waucka
Timestamp=Tue 2015-04-07 10:00:27 CDT
TimestampMonotonic=52615045
VTNr=1
Display=:0
Remote=no
Service=sddm
Desktop=KDE
Scope=session-c2.scope
Leader=514
Audit=0
Type=x11
Class=user
Active=yes
State=active
IdleHint=no
IdleSinceHint=0
IdleSinceHintMonotonic=0

<Press Alt+Left>

$ loginctl show-session c2
Id=c2
Name=waucka
Timestamp=Tue 2015-04-07 10:00:27 CDT
TimestampMonotonic=52615045
VTNr=1
Display=:0
Remote=no
Service=sddm
Desktop=KDE
Scope=session-c2.scope
Leader=514
Audit=0
Type=x11
Class=user
Active=no
State=online
IdleHint=no
IdleSinceHint=0
IdleSinceHintMonotonic=0

$ loginctl list-sessions
   SESSION        UID USER             SEAT            
        c1        996 sddm             seat0           
        c2       1000 waucka           seat0           

2 sessions listed.