GDM Autologin (revisited)

The following is the configuration for that.

1) install RHEL7.3 with minimum install
2) install gdm and dependencies
3) install motif, xterm, xorg-x11-fonts-*, xorg-x11-server-Xorg and xorg-x11-xinit-session
4) systemctl set-default graphical.target
5) create /root/.Xclients  (This is called from /etc/X11/xinit/xinitrc)
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#!/bin/sh
xclock -geometry +0+0 &
xterm -ls &

exec /usr/bin/mwm -multiscreen
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6) create /root/.xsession  (This is called from /usr/libexec/xinit-compat)
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#!/bin/sh
exec /etc/X11/xinit/xinitrc
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7) set exec permission to /root/.Xclients and ~/.xsession

# chmod gu+x /root/.Xclients /root/.xsession

8) create /etc/sysconfig/desktop. This is to disable gnome and kde completely
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unset GSESSION
unset STARTKDE
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9) create /etc/gdm/custom.conf. This is to enable automatic login with root user.
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[daemon]
AutomaticLogin=root
AutomaticLoginEnable=True
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Reboot, and mwm should start on the screen without any login step.