XDG_RUNTIME_DIR not set in the environment

[Brainslug]

Hi,

I would appreciate some help with running programs in X (WindowMaker) as another user.

Until recently (Debian Stretch) I was able to run graphical programs in X as a second user, like so:

- log into X as user1
- run "xhost+"
- run "su - user2"
- run any graphical program (gthumb, konquerer, ...) as user2

Now when I try to run a program as user2, I get

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 user2@localhost:~$ gthumb
 error: XDG_RUNTIME_DIR not set in the environment.
 Segmentation fault 

XDG_RUNTIME_DIR for user1 points to /run/user/1000 which I believe gets created by pam_systemd when logging into X. However, doing "su - user2" does not create /run/user/1001. Why not? And how do I get on-the-fly user switching working again?
Related to this, /run/user/1001 not being created on user switch has always caused me some grief b/c audio would not work for user2. But I could work around that by piping pulse through a socket. But now graphics are also broken and that I can't seem to work around.

Any help would be much appreciated!

[Head_on_a_Stick]

Can you not just use:

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XDG_RUNTIME_DIR=/run/user/1001 gthumb

EDIT: I think your problem stems from version >1.16 of Xorg being rootless; this requires all sessions to be launched from the same TTY from which the user logged on.

[Brainslug]

Hi,

unfortunately,

XDG_RUNTIME_DIR=/run/user/1001 gthumb

does not work either. I can set the variable and the error message goes away, but gthumb (or any other program) still segfaults, because /run/user/1001 does not exist and I can't get pam_systemd to create it on user switching.

I think your problem stems from version >1.16 of Xorg being rootless; this requires all sessions to be launched from the same TTY from which the user logged on.

This is a good point. With systemd.logind taking over login handling a lot of the things I used to be able to do on my system just broke. However, except for audio, the graphical switching was still working after X 1.16 was introduced and even long into 1.17. Just recently this stopped working. I think this is a major regression in X and makes my live fairly miserable. I can understand that "su - user2" may no longer work with the way login is now handled, but X-forwarding via ssh should still work, "ssh -X user2@localhost" -- it doesn't.

Any ideas, anyone? I thought linux was a multi-user system, but now it's like Win3.1, back to just one user at a time...

Thanks!

[Brainslug]

strange - after the latest libstdc++6 / gcc upgrade (5.2.1-23) , things are working again. I can "su - user2" and fire up all the GUIs as before.

Not sure what exactly fixed the problem (or broke things in the first place), but I'm glad it's working again.

Thanks!