I decided to full upgrade an Ubuntu MATE from 18.04 LTS to 22.04.1 LTS. That meant multiple upgrades, first to 20.04, then 22.04.1. I used the Software Updater application, not the command line based on a coin toss. Ubuntu MATE uses LightDM as the display manager.
When the first upgrade completed, I noticed that the Guest login reappeared. When I looked for /etc/lightdm/lightdm.conf, it was gone. It had been replaced by the file /etc/lightdm/users.conf and a directory /etc/lighdm/lighdm.conf.d. The lightdm.conf.d directory contains three files: "90-arctica-greeter.conf", "91-arctica-greeter-guest-session.conf" and "91-arctica-greeter-mate.conf". Note that two of the files start with "91".
I am used to editing lightdm.conf as a single file. LightDM is not the only configuration that has changed over time from a .conf file to a .conf.d directory structure. Sometimes the name-matching xxxxx.conf file and xxxxx.conf.d are both in a directory. (Yes, I have seen other ".d" directories and edited files in them, but followed the pattern without a real understanding. Network configuration files changed a long time ago to a similar format in some versions, but I never fully understood the workings of those changes. That is what I am asking about now.)
My normal habit is to copy the file to back it up just in case. I append ".org" to the copy, then edit the .conf file.
Here are my questions:
1. Where can I find links or documentation regarding how those configuration directories work?
What I am struggling with is that they seem to be processed in filename order. In the new LightDM, two of the filenames start with the same numerical prefix. Do all xxxxx.conf.d directories work the same? How are multiple files with the same prefix read or skipped or is the prefix ignored and all files are read in sort order? How do they handle multiple files with overlapping or duplicate configuration entries?
-> Will ".org" files be read and interpreted from those xxxxx.conf.d directories?
2. Where can I find links or documentation regarding the various configuration settings for LightDM configuration files? Could they be distro-specific?
3. And ... What obvious things am I missing or failing to understand?
When the first upgrade completed, I noticed that the Guest login reappeared. When I looked for /etc/lightdm/lightdm.conf, it was gone. It had been replaced by the file /etc/lightdm/users.conf and a directory /etc/lighdm/lighdm.conf.d. The lightdm.conf.d directory contains three files: "90-arctica-greeter.conf", "91-arctica-greeter-guest-session.conf" and "91-arctica-greeter-mate.conf". Note that two of the files start with "91".
I am used to editing lightdm.conf as a single file. LightDM is not the only configuration that has changed over time from a .conf file to a .conf.d directory structure. Sometimes the name-matching xxxxx.conf file and xxxxx.conf.d are both in a directory. (Yes, I have seen other ".d" directories and edited files in them, but followed the pattern without a real understanding. Network configuration files changed a long time ago to a similar format in some versions, but I never fully understood the workings of those changes. That is what I am asking about now.)
My normal habit is to copy the file to back it up just in case. I append ".org" to the copy, then edit the .conf file.
Here are my questions:
1. Where can I find links or documentation regarding how those configuration directories work?
What I am struggling with is that they seem to be processed in filename order. In the new LightDM, two of the filenames start with the same numerical prefix. Do all xxxxx.conf.d directories work the same? How are multiple files with the same prefix read or skipped or is the prefix ignored and all files are read in sort order? How do they handle multiple files with overlapping or duplicate configuration entries?
-> Will ".org" files be read and interpreted from those xxxxx.conf.d directories?
2. Where can I find links or documentation regarding the various configuration settings for LightDM configuration files? Could they be distro-specific?
3. And ... What obvious things am I missing or failing to understand?