xdm authenticates but does not start Xfce
 

xdm authenticates but does not start Xfce. This is supported by: if an invalid combination of user name and password is entered, xdm clears the fields and displays "Login incorrect or forbidden by policy" and an entry appears in /var/log/secure.

This is a personal workstation; xdm behaves the same way for both root and the user.

The user's Xfce setup is OK. If the user logs on at a virtual terminal and runs startx, the Xfce desktop starts and functions normally. When the desktop session is locked, XScreenSaver accepts username and password normally and unlocks the screen.

AIUI, when xdm has authenticated, it runs /etc/X11/xinit/xinitrc. That is a symlink to /etc/X11/xinit/xinitrc.xfce, a /bin/sh script. I added debug logging to that script:
but the log file was not created.

Whatever is happening, it seems to be happening within xdm. rc.4 was modified, adding the -error option to xdm startup. Retesting and examining the log, I could find no clues.

rc.4 was further modified, adding debug=1. The man page warns, "To interpret these debugging messages, a copy of the source code for xdm is almost a necessity. No attempt has been made to rationalize or standardize the output". Fair warning; I cannot even confidently identify the point at which the attempted login has failed and xdm starts to re-initialise the login screen. In case it is meaningful to LQ members, here it is, starting after login and password are entered and Enter pressed
and, for comparison, here's how it looks when xdm is killed and it is re-started via inittab

xdm looks for $HOME/.xsession. I also use XFCE and it is a copy of $HOME/.xinitrc but it should have executable permission. Running xwmconfig should do this automatically.

Are you on Slackware 14.0? If I remember well, on Slackware 13.37, the xdm choice of Window Manager depended on the xwmconfig choice for root, but I might be wrong.

Thanks ChrisAbela :)

Yes, this is Slackware64 14.0. It is a fresh a installation on a computer that was previously running Slackware64 13.37. During installation Xfce was chosen as the desktop. Hence /etc/X11/xinit/xinitrc being a symlink to /etc/X11/xinit/xinitrc.xfce.

I don't have access to the computer at the moment but the installation log says the user's .xsession was not copied from the 13,37 installation. Regards X, only .Xmodmap, .Xresources and .xscreensaver were copied -- no .xsession or .xinitrc. But it is unlikely that the problem is triggered by such files because the problem occurs when root tries to login at the xdm screen and no such files were copied from 13.37 for root.

I can explore xwmconfig tomorrow.

Since you are talking about a personal workstation, do you really need a login manager?

I have replaced it with a very simple script in my .profile that starts X depending which runlevel the box was started in, and i have made the 5th runlevel in /etc/initab to be the same as runlevel 3. So if i start init 3 i just get a normal console after login, but if i start init 5 startx is issued automatically after login.

I use Icewm that is started from my .xinitrc and by that simple script i do not need any login manager at all, if you do not need any fancy things a login manager provides, i think you can do the same using xfce.

Thanks steelneck, that's neat :)

I fixed it by re-installing so am marking this thread SOLVED although a solution was not identified. In case anyone wants me to try some analysis, I will keep a backup of the defective system for a while.