How to return the currently active user/session on a graphical Linux desktop session?

Question

My question is how to get the user name on the shell, who is currently using the Linux desktop (on a "normal" desktop system, where you usually only have one active user, i.e. no server system here, but just your usual Laptop etc.). If you really want to imagine a server system, I would be fine with listing all active users.

So take e.g. the case that a script is running as root as a cron job (or similar) and I want to get the/all currently active users on the system.

I know I could use w or who or users to get the currently logged in users. That's fine, but that user are logged in does not mean that they are actually currently using the desktop, because in all desktop environments I know, users can switch to another user after they have logged in.
I could also use last to get the user who last logged in, but this is also no guarantee that this user is still the active one.

So how can one do this? It is fine to provide specific solutions for different desktops environments (GNOME, KDE, …), but, of course, a cross-compatible solution is preferred.

Solution

On many current distributions, login sessions (graphical and non-graphical) are managed by logind. You can list sessions using

loginctl list-sessions

and then display each session’s properties using

loginctl show-session ${SESSIONID}

or

loginctl session-status ${SESSIONID}

(replacing ${SESSIONID} as appropriate); the difference between the two variants is that show-session is designed to be easily parsed, session-status is designed for human consumption. Active sessions are identified by their state; you can query that directly using

loginctl show-session -p State ${SESSIONID}

which will output

State=active

for the active session(s). The full show-session output will tell you which user is connected, which TTY is being used, whether it’s a remote session, whether it’s a graphical session etc.

Note that logind can have multiple active sessions, if the system is configured with multiple seats, or if there are remote sessions.

Putting this all together,

for sessionid in $(loginctl list-sessions --no-legend | awk '{ print $1 }')
do loginctl show-session -p Id -p Name -p User -p State -p Type -p Remote $sessionid
done

will give all the information you need to determine which sessions are active and who is using them, and

for sessionid in $(loginctl list-sessions --no-legend | awk '{ print $1 }')
do loginctl show-session -p Id -p Name -p User -p State -p Type -p Remote $sessionid | sort
done |
awk -F= '/Name/ { name = $2 } /User/ { user = $2 } /State/ { state = $2 } /Type/ { type = $2 } /Remote/ { remote = $2 } /User/ && remote == "no" && state == "active" && (type == "x11" || type == "wayland") { print user, name }'

will print the identifiers and logins of all active users with graphical sessions.

The LockedHint property now indicates whether a given session is locked, so

for sessionid in $(loginctl list-sessions --no-legend | awk '{ print $1 }')
do loginctl show-session -p Id -p Name -p User -p State -p Type -p Remote -p LockedHint $sessionid | sort
done |
awk -F= '/Name/ { name = $2 } /User/ { user = $2 } /State/ { state = $2 } /Type/ { type = $2 } /Remote/ { remote = $2 } /LockedHint/ { locked = $2 } /User/ && remote == "no" && state == "active" && (type == "x11" || type == "wayland") { print user, name, locked == "yes" ? "locked" : "unlocked" }'

will also indicate whether the active session is locked or not.

Comments

[roaima]

My Linux-based laptop can often have two users logged in on it simultaneously. It's also possible that I'm actually using a vTerminal session outside the GUI (Ctrl+Alt+F1). In your terms, which one's active?

[wvxvw]

If, for example, your Linux uses systemd and lightdm (a setup typical for many modern stock Linuxes), you could examine the output of systemctl status lightdm and look for the line "session opened for user <user name> by <user id>".

[rsm]

what do you mean by active user? on linux you can have any number of active users.

[rugk]

@roaima Personally I only care about the graphical sessions (so no terminal) and I only care about the user, whose session is currently active, i.e. using it. As I said when using the device as a server, of course multiple users could be active, but do not imagine this case. Or, if you want, list all active users… My use case would be a simple Laptop/PC Linux installation, where usually only one user can be active…

[rugk]

@wvxvw Thanks, but this only works with lightdm. gdm e.g. does not show me this information.

[roaima]

If you have a particular definition for "active", as in your comment above, please add it to your question for everyone to see. That's how this site works.

[roaima]

Out of interest, what are you hoping to do with the knowledge of the active user? Send them a message? If so, rather than trying to identify the correct "active" user why not send it to all currently logged in users.

[Hunter.S.Thompson]

"I know I could use w or who or users to get the currently logged in users." @dessert OP wants to know which users are active and not idle

[dessert]

@Hunter.S.Thompson OP does not speak of multiple users but rather explicitly just of the user name and the active one. w or who or users don't do the same as whoami, plus even if OP meant another thing (and needs to clarify the question then) other people actually searching for whoami will probably land here.

[rugk]

I clarified the question, so of course it is easy to get the currently active user, when the script I run runs under that user. But my script runs e.g. as a cron job in a different context, so I cannot just ask "Who am I?"…

[dessert]

@rugk Instead of downvoting my answer you should add that information to your question and furthermore clarify how a user using the desktop is defined exactly.

[rugk]

That returns gdm in my case…

[rugk]

It's already there. First sentence/paragraph.

[Bachi]

I wonder if there's a way to find out if a graphical session is locked or 'open'. In both cases "State=active" is displayed as it seems.

[Stephen Kitt]

@Bachi see LockedHint, described in the updated answer.

[Vir]

loginctl lock-session 3; sleep 10; loginctl show-session -p LockedHint 3 prints LockedHint=no. Do you know whether this hint depends on the desktop environment, or did I simply hit a bug?

[Vir]

yes. loginctl unlock-session 3 also unlocks it again

[Stephen Kitt]

@Vir from the looks of things, loginctl doesn’t set the hint; the hint only changes in response to d-bus messages from the DE.