Comment # 23 on bug 1013200 from Patrick Schaaf

(In reply to Egbert Eich from comment #20)
>
> When the Xserver is running but just showing a black screen one could try to
> obtain the credentials from the Xserver command line and then try to log in:
> From a root shell (remote or after a VT switch) do:
>  1. # ps aux | grep Xorg
>     get the argument after '-auth'
>  2. # export XAUTHORITY=<the_argument>
>  3. # export DISPLAY=:0.0
>  4. # xterm

That doesn't work... See transscript below. I also tried it as user, with
/run/addm/{...} chmodded 644, still no joy.

rofl:~ # systemctl status display-manager
display-manager.service - X Display Manager
   Loaded: loaded (/usr/lib/systemd/system/display-manager.service; enabled;
vendor preset: enabled)
   Active: ^[[0;1;32mactive (running)^[[0m since Fri 2016-12-02 16:10:35 CET;
2min 1s ago
  Process: 1300 ExecStart=/usr/lib/X11/display-manager start (code=exited,
status=0/SUCCESS)
 Main PID: 1390 (sddm)
    Tasks: 4 (limit: 512)
   CGroup: /system.slice/display-manager.service
           ������1390 /usr/bin/sddm
           ������1402 /usr/bin/X -nolisten tcp -auth
/run/sddm/{b8afb90f-46c8-4438-9a97-1bf82d128e7b} -background none -noreset
-displayfd 18 vt7

Dec 02 16:10:36 linux sddm[1390]: Socket server started.
Dec 02 16:10:36 linux sddm[1390]: Greeter starting...
Dec 02 16:10:36 linux sddm[1390]: Adding cookie to
"/run/sddm/{b8afb90f-46c8-4438-9a97-1bf82d128e7b}"
Dec 02 16:10:36 linux sddm-helper[1671]: [PAM] Starting...
Dec 02 16:10:36 linux sddm-helper[1671]: [PAM] Authenticating...
Dec 02 16:10:36 linux sddm-helper[1671]: [PAM] returning.
Dec 02 16:10:36 linux sddm-helper[1671]: pam_unix(sddm-greeter:session):
session opened for user sddm by (uid=0)
Dec 02 16:10:53 rofl sddm[1390]: Greeter session started successfully
Dec 02 16:10:53 rofl sddm[1390]: ^[[0;1;39mAuth: sddm-helper exited with 6^[[0m
Dec 02 16:10:53 rofl sddm[1390]: Greeter stopped.
rofl:~ # coredumpctl list
TIME                            PID   UID   GID SIG PRESENT EXE
[... stuff from previous boots ...]
Fri 2016-12-02 16:10:54 CET    2045   481   479   6 * /usr/bin/sddm-greeter
rofl:~ # export XAUTHORITY=/run/sddm/{b8afb90f-46c8-4438-9a97-1bf82d128e7b\}
rofl:~ # export DISPLAY=:0.0
rofl:~ # xterm
No protocol specified
Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
xterm: Xt error: Can't open display: %s