# cat /usr/share/xgreeters/lightdm-gtk-greeter.desktop
[Desktop Entry]
Name=LightDM GTK+ Greeter
Comment=This runs the GTK+ greeter, it should only be run from LightDM
Exec=x11trace -D :11 -d :0 -b -o /var/log/lightdm/x11trace.log /sbin/lightdm-gtk-greeter
Type=Application


# grep -v '^#\|^$' /etc/lightdm/lightdm.conf
[LightDM]
minimum-vt=1
[Seat:*]
session-wrapper=/etc/X11/xinit/Xsession


# cat /var/log/lightdm/lightdm.log
[+6.55s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+6.55s] DEBUG: Starting Light Display Manager 1.15.0, UID=0 PID=1105
[+6.55s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+6.55s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+6.55s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+6.55s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+6.55s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+6.55s] DEBUG: Registered seat module xlocal
[+6.55s] DEBUG: Registered seat module xremote
[+6.55s] DEBUG: Registered seat module unity
[+6.56s] DEBUG: Monitoring logind for seats
[+6.56s] DEBUG: New seat added from logind: seat0
[+6.56s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+6.56s] DEBUG: Seat seat0: Loading properties from config section SeatDefaults
[+6.56s] DEBUG: Seat seat0: Starting
[+6.56s] DEBUG: Seat seat0: Creating greeter session
[+6.81s] DEBUG: Seat seat0: Creating display server of type x
[+7.13s] DEBUG: Using VT 1
[+7.13s] DEBUG: Seat seat0: Starting local X display on VT 1
[+7.13s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+7.13s] DEBUG: DisplayServer x-0: Writing X server authority to /var/run/lightdm/root/:0
[+7.13s] DEBUG: DisplayServer x-0: Launching X Server
[+7.13s] DEBUG: Launching process 1255: /usr/bin/X :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt1 -novtswitch
[+7.13s] DEBUG: DisplayServer x-0: Waiting for ready signal from X server :0
[+7.13s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+7.14s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+7.17s] DEBUG: Loading users from org.freedesktop.Accounts
[+7.17s] DEBUG: User /org/freedesktop/Accounts/User1005 added
[+7.17s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+18.84s] DEBUG: Got signal 10 from process 1255
[+18.84s] DEBUG: DisplayServer x-0: Got signal from X server :0
[+18.84s] DEBUG: DisplayServer x-0: Connecting to XServer :0
[+18.84s] DEBUG: Seat seat0: Display server ready, starting session authentication
[+18.84s] DEBUG: Session pid=1651: Started with service 'lightdm-greeter', username 'lightdm'
[+19.36s] DEBUG: Session pid=1651: Authentication complete with return value 0: Success
[+19.36s] DEBUG: Seat seat0: Session authenticated, running command
[+19.36s] DEBUG: Session pid=1651: Running command /usr/bin/x11trace -D :11 -d :0 -b -o /var/log/lightdm/x11trace.log /sbin/lightdm-gtk-greeter
[+19.36s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm
[+19.38s] DEBUG: Session pid=1651: Logging to /var/log/lightdm/x-0-greeter.log
[+20.21s] DEBUG: Activating VT 1
[+20.21s] DEBUG: Activating login1 session c1
[+20.21s] DEBUG: Seat seat0 changes active session to c1
[+20.21s] DEBUG: Session c1 is already active
[+21.17s] DEBUG: Session pid=1651: Greeter connected version=1.15.0 resettable=false
[+31.15s] DEBUG: Session pid=1651: Greeter start authentication for xfce
[+31.15s] DEBUG: Session pid=1746: Started with service 'lightdm', username 'xfce'
[+31.45s] DEBUG: Session pid=1746: Got 1 message(s) from PAM
[+31.45s] DEBUG: Session pid=1651: Prompt greeter with 1 message(s)
[+85.24s] DEBUG: Got signal 15 from process 1
[+85.24s] DEBUG: Caught Terminated signal, shutting down
[+85.24s] DEBUG: Stopping display manager
[+85.24s] DEBUG: Seat seat0: Stopping
[+85.24s] DEBUG: Seat seat0: Stopping display server
[+85.24s] DEBUG: Sending signal 15 to process 1255
[+85.24s] DEBUG: Seat seat0: Stopping session
[+85.24s] DEBUG: Session pid=1651: Sending SIGTERM
[+85.24s] DEBUG: Seat seat0: Stopping session
[+85.24s] DEBUG: Session pid=1746: Sending SIGTERM
[+85.24s] DEBUG: Session pid=1651: Terminated with signal 1
[+85.24s] DEBUG: Seat seat0: Session stopped
[+85.24s] DEBUG: Session pid=1746: Terminated with signal 15
[+85.24s] DEBUG: Session: Failed during authentication
[+85.24s] DEBUG: Seat seat0: Session stopped
[+86.12s] DEBUG: Process 1255 exited with return value 0
[+86.12s] DEBUG: DisplayServer x-0: X server stopped
[+86.12s] DEBUG: Releasing VT 1
[+86.12s] DEBUG: DisplayServer x-0: Removing X server authority /var/run/lightdm/root/:0
[+86.12s] DEBUG: Seat seat0: Display server stopped
[+86.12s] DEBUG: Seat seat0: Stopped
[+86.12s] DEBUG: Display manager stopped
[+86.12s] DEBUG: Stopping daemon
[+86.12s] DEBUG: Exiting with return value 0


# grep -v '^#\|^$' /etc/lightdm/lightdm-gtk-greeter.conf
[greeter]
background=/usr/share/backgrounds/f21/default/tv-wide/f21.png
user-background=false
theme-name=Greybird
icon-theme-name=Fedora
allow-debugging=true


# file /usr/share/backgrounds/f21/default/tv-wide/f21.png
/usr/share/backgrounds/f21/default/tv-wide/f21.png: PNG image data, 1920 x 1080, 8-bit/color RGBA, non-interlaced


# cat /var/log/lightdm/x-0-greeter.log
** Message: Starting lightdm-gtk-greeter 2.0.1 (May 21 2015, 13:33:35)
** Message: [Configuration] Reading file: /etc/lightdm/lightdm-gtk-greeter.conf
Got connection from unknown(local)
DEBUG-Message: Connecting to display manager...
DEBUG-Message: Wrote 22 bytes to daemon
DEBUG-Message: Read 8 bytes from daemon
DEBUG-Message: Read 152 bytes from daemon
DEBUG-Message: Connected version=1.15.0 default-session=default show-manual-login=false hide-users=false has-guest-account=false show-remote-login=true
DEBUG-Message: [Configuration] Changing GTK+ theme to 'Greybird'
DEBUG-Message: [Configuration] GTK+ theme: 'Greybird'
DEBUG-Message: [Configuration] Changing icons theme to 'Fedora'
DEBUG-Message: [Configuration] Icons theme: 'Fedora'
DEBUG-Message: [Configuration] Changing font to 'Sans 10'
DEBUG-Message: [Configuration] Font: 'Sans 10'

** (lightdm-gtk-greeter:1696): WARNING **: [PIDs] Failed to execute command: /usr/lib/at-spi2-core/at-spi-bus-launcher

** (lightdm-gtk-greeter:1696): WARNING **: [PIDs] Failed to execute command: upstart
DEBUG-Message: Loaded session /usr/share/xsessions/xfce.desktop (Xfce Session, Use this session to run Xfce as your desktop environment)
DEBUG-Message: [Configuration] Monitor configuration found: '*'
DEBUG-Message: [Background] Connecting to screen: 0x7fe4eeb3e0d0 (1920x1080px, 508x285mm)
DEBUG-Message: [Background] Monitors found: 1
DEBUG-Message: [Background] Monitor: DVI-I-1 #0 (1920x1080 at 0x0) primary
DEBUG-Message: [Background] No configuration options for monitor DVI-I-1 #0, using default
DEBUG-Message: [Background] Pointer position will be used to set active monitor: 960x540
DEBUG-Message: [Background] Active monitor changed to: DVI-I-1 #0
DEBUG-Message: Loading users from org.freedesktop.Accounts
DEBUG-Message: User /org/freedesktop/Accounts/User1005 added
DEBUG-Message: User /org/freedesktop/Accounts/User1000 added
DEBUG-Message: Loading sessions from org.freedesktop.DisplayManager
DEBUG-Message: Failed to load user image: Failed to open file '/home/xfce/.face': Permission denied
DEBUG-Message: Starting authentication for user xfce...
DEBUG-Message: Wrote 20 bytes to daemon
Got connection from unknown(local)
Got connection from unknown(local)
DEBUG-Message: Run Gtk loop...
DEBUG-Message: Read 8 bytes from daemon
DEBUG-Message: Read 34 bytes from daemon
DEBUG-Message: Prompt user with 1 message(s)


# ls -lh /var/log/lightdm/x11trace.log
-rw-r--r--. 1 lightdm lightdm 7.8M May 29 06:00 /var/log/lightdm/x11trace.log