Primero lo primero, hola :)
Salí systemctl disable lightdm.servicedel modo de recuperación.
Después de eso reinicié mi PC y escribí sudo lightdm start ; startx. Comencé una sección gráfica pero cuando intenté iniciar un programa gtk desde la terminal recibí este error:
Unable to init server: No se pudo conectar: Conexión rehusada
(nautilus:14383): Gtk-WARNING **: 10:27:51.240: cannot open display: :1
y cuando me di cuenta, inicié lightdm en modo de depuración sudo lightdm --debug starty obtuve esto:
[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.26.0, UID=0 PID=13909
[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-unity.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
[+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using Xephyr for X servers
[+0.00s] DEBUG: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Registered seat module unity
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: Monitoring logind for seats
[+0.01s] DEBUG: New seat added from logind: seat0
[+0.01s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.01s] DEBUG: Seat seat0: Starting
[+0.01s] DEBUG: Seat seat0: Creating user session
[+0.02s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+0.02s] DEBUG: Seat seat0: Creating display server of type x
[+0.04s] DEBUG: Using VT 7
[+0.04s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.04s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.04s] DEBUG: XServer 0: Writing X server authority to /var/run/lightdm/root/:0
[+0.04s] DEBUG: XServer 0: Launching X Server
[+0.04s] DEBUG: Launching process 13915: /usr/bin/Xephyr :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.04s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.04s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.04s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.09s] DEBUG: Process 13915 exited with return value 1
[+0.09s] DEBUG: XServer 0: X server stopped
[+0.09s] DEBUG: Releasing VT 7
[+0.09s] DEBUG: XServer 0: Removing X server authority /var/run/lightdm/root/:0
[+0.09s] DEBUG: Seat seat0: Display server stopped
[+0.09s] DEBUG: Seat seat0: Stopping session
[+0.09s] DEBUG: Seat seat0: Session stopped
[+0.09s] DEBUG: Seat seat0: Stopping display server, no sessions require it
[+0.09s] DEBUG: Seat seat0: Active display server stopped, starting greeter
[+0.09s] DEBUG: Seat seat0: Creating greeter session
[+0.09s] DEBUG: Seat seat0: Creating display server of type x
[+0.09s] DEBUG: Using VT 7
[+0.09s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.09s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.09s] DEBUG: XServer 0: Writing X server authority to /var/run/lightdm/root/:0
[+0.09s] DEBUG: XServer 0: Launching X Server
[+0.09s] DEBUG: Launching process 13916: /usr/bin/Xephyr :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.09s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.10s] DEBUG: Process 13916 exited with return value 1
[+0.10s] DEBUG: XServer 0: X server stopped
[+0.10s] DEBUG: Releasing VT 7
[+0.10s] DEBUG: XServer 0: Removing X server authority /var/run/lightdm/root/:0
[+0.10s] DEBUG: Seat seat0: Display server stopped
[+0.10s] DEBUG: Seat seat0: Stopping session
[+0.10s] DEBUG: Seat seat0: Session stopped
[+0.10s] DEBUG: Seat seat0: Stopping display server, no sessions require it
[+0.10s] DEBUG: Seat seat0: Stopping; greeter display server failed to start
[+0.10s] DEBUG: Seat seat0: Stopping
[+0.10s] DEBUG: Seat seat0: Stopped
[+0.10s] DEBUG: Required seat has stopped
[+0.10s] DEBUG: Stopping display manager
[+0.10s] DEBUG: Display manager stopped
[+0.10s] DEBUG: Stopping daemon
[+0.11s] DEBUG: Exiting with return value 1
Pude iniciar programas gtk antes de ejecutarlos, systemctl disable lightdm.serviceasí que probablemente esa sea la fuente del problema.
Si entendí bien systemctl disable lightdm.servicees no iniciar lightdm automáticamente, no hacer que no pueda ejecutarse, así que no lo sé.
¿Tiene alguna sugerencia para resolver el problema?