[SOLVED] Installing Lightdm on CentOS 7.5

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desertcat
Posts: 417
Joined: 2014/08/07 02:17:29
Location: Tucson, AZ

[SOLVED] Installing Lightdm on CentOS 7.5

Post by desertcat » 2018/05/22 17:00:16

With the release of CentOS 7.5 whatever was the link between CentOS 7.x and sddm was broken leaving only a BLACK SCREEN in its wake, forcing the user to have to use gdm, a display manager that lead to a a runaway process that simply filled up the /var partition. The major cause which we soon re-discovered was anything that routinely monitored the computer such as GKRellM, Gnome System Monitor, et al. To prevent the process from eating up the partition with useless magic cookies and Audit files, you just killed all processes that had a monitoring function.

https://www.centos.org/forums/viewtopic ... 47&t=62294

Ideally I wanted my sddm back, but as alternative I was willing to install lightdm, another display manager with really high marks. I did not particularly care if it was lightdm, sddm, or any other dm so long as it was NOT gdm. Several attempts were made in install both sddm and lightdm, but regardless of the effort I still ended up with the cursed BLACK SCREEN. I then stumbled over an article I thought was worth a try, as all other methods had failed.

https://www.systutorials.com/241151/how ... on-fedora/

Assuming you are running KDE => GoTo a konsole => type su => Enter Secret Sauce Password and become root!

As root enter the following two commands:

systemctl disable gdm.service
systemctl enable lightdm.service


Reboot the Machine and it should come up in lightdm

There is just one teeny tiny fly in the ointment: I did not see a way to switch to another Desktop Environment. Thus if you routinely switch between different Desktop Environments you are hosed unless some one can enlighten me how it can be done. Given that I am a single user on the workstation, and the only other person who occasional works on it is my buddy who also uses KDE as his preferred Desktop Environment, this is not a a problem, but still is annoyance as I have multiple DE on this machine.

Apparently if you were already using lightdm before the rollover you were not impacted.

As with sddm the Case of the Runaway Processes has been [SOLVED] (Caveat Emptor -- ... unless Red Hat manages to screw this one up too!)

desertcat
Posts: 417
Joined: 2014/08/07 02:17:29
Location: Tucson, AZ

Re: [SOLVED] Installing Lightdm on CentOS 7.5

Post by desertcat » 2018/05/23 14:40:15

desertcat wrote: Snip
There is just one teeny tiny fly in the ointment: I did not see a way to switch to another Desktop Environment. Thus if you routinely switch between different Desktop Environments you are hosed unless some one can enlighten me how it can be done. Given that I am a single user on the workstation, and the only other person who occasional works on it is my buddy who also uses KDE as his preferred Desktop Environment, this is not a a problem, but still is annoyance as I have multiple DE on this machine.

Apparently if you were already using lightdm before the rollover you were not impacted.

As with sddm the Case of the Runaway Processes has been [SOLVED] (Caveat Emptor -- ... unless Red Hat manages to screw this one up too!)
Another problem [SOLVED]: Apparently there are two versions of the Lightdm.greeter. There is the lightdm-gtk-greeter.conf and then there is the lightdm-kde-greeter.conf. I discovered this by accident while comparing notes with my buddy who has now switched to lightdm, but had a vastly different login screen. When we went to /etc/lightdm/... I had the gtk version while he had the kde version. He had no problem switching to a different Desktop Environment (DE), such as KDE, GNOME, MATE, etc. but I seemly could not. I then noticed I had a white strip along the top, that looked very "GNOME-like" with some very small symbols. A quick exploration of each symbol showed what each does. One looks like a page (?) with some text (?) on it though the thing is so small it really is hard to tell exactly what it is. When I clicked on it Lo-and-Behold there was a listing of ALL my installed DE. My buddy had the kde version with it larger symbols etc. and more familiar layout.

BTW there is one thing I quickly discovered. It is very easy to customize the greeter presentation. My Greeter showed the rather dull and uninspiring CentOS 7 "Day" background, my buddy had this rather cool pattern version. There is a line that is uncommented out in each version that says something like:
[Greeter]
background=/usr/share/backgrounds/default

If you go to /usr/share/backgrounds there are a whole bunch of wallpapers that are there. There are a whole lot more in /usr/share/wallpapers I found one called "Abstract-(long_name).png" I really liked that was filled with color. First I shortened and renamed the file to Abstract.png. Second I ran ls -l to check permissions and ownership. In this case it was owned by "dcat". You need to make sure it is owned by root. Run chown root:root Abstract.png confirm it is now owned by root by running ls -l. Third using your choice of a file editor such as vim, sublime, or mc swap Abstract.png for "default", save, and then reboot your machine. PRESTO!! You now have a Customized Greeter!!!

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