[Bug 1595454] [NEW] systemctl cannot reenable lightdm (with workaround)

[Ulli Horlacher]

Public bug reported:

This is on xubuntu 16.04 with systemd 229-4ubuntu6:

systemctl cannot reenable lightdm

I have deactivated lightdm with:

root at tux:~# systemctl disable lightdm
root at tux:~# reboot

Works as expected: lightdm does not start any more.

Then I tried to reenable it with:

root at tux:~# systemctl enable lightdm
root at tux:~# reboot

root at tux:~# systemctl reenable lightdm
root at tux:~# reboot


But lightdm still does not start any more!
I have to start lightdm manually with:

root at tux:~# systemctl start lightdm

root at tux:~# systemctl is-enabled lightdm
static

root at tux:~# systemctl status lightdm
* lightdm.service - Light Display Manager
   Loaded: loaded (/lib/systemd/system/lightdm.service; static; vendor preset: e
   Active: active (running) since Wed 2016-06-22 11:06:16 CEST; 12s ago
     Docs: man:lightdm(1)
  Process: 1803 ExecStartPre=/bin/sh -c [ "$(basename $(cat /etc/X11/default-dis
 Main PID: 1810 (lightdm)
   CGroup: /system.slice/lightdm.service
           |-1810 /usr/sbin/lightdm
           `-1822 /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm


I found a workaround, after:

root at tux:~# ln -s /lib/systemd/system/lightdm.service /etc/systemd/system/display-manager.service
root at tux:~# reboot

lightdm is starting again automatically at boot time.

"systemctl enable lightdm" does not restore this link! 
This is the bug.


root at tux:~# systemctl --version
systemd 229
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ -LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1595454

Title:
  systemctl cannot reenable lightdm (with workaround)

Status in systemd package in Ubuntu:
  New

Bug description:
  This is on xubuntu 16.04 with systemd 229-4ubuntu6:

  systemctl cannot reenable lightdm

  I have deactivated lightdm with:

  root at tux:~# systemctl disable lightdm
  root at tux:~# reboot

  Works as expected: lightdm does not start any more.

  Then I tried to reenable it with:

  root at tux:~# systemctl enable lightdm
  root at tux:~# reboot

  root at tux:~# systemctl reenable lightdm
  root at tux:~# reboot

  
  But lightdm still does not start any more!
  I have to start lightdm manually with:

  root at tux:~# systemctl start lightdm

  root at tux:~# systemctl is-enabled lightdm
  static

  root at tux:~# systemctl status lightdm
  * lightdm.service - Light Display Manager
     Loaded: loaded (/lib/systemd/system/lightdm.service; static; vendor preset: e
     Active: active (running) since Wed 2016-06-22 11:06:16 CEST; 12s ago
       Docs: man:lightdm(1)
    Process: 1803 ExecStartPre=/bin/sh -c [ "$(basename $(cat /etc/X11/default-dis
   Main PID: 1810 (lightdm)
     CGroup: /system.slice/lightdm.service
             |-1810 /usr/sbin/lightdm
             `-1822 /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm

  
  I found a workaround, after:

  root at tux:~# ln -s /lib/systemd/system/lightdm.service /etc/systemd/system/display-manager.service
  root at tux:~# reboot

  lightdm is starting again automatically at boot time.

  "systemctl enable lightdm" does not restore this link! 
  This is the bug.

  
  root at tux:~# systemctl --version
  systemd 229
  +PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ -LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN

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