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Inspired_Blue
Asked: 2021-01-06 10:24:02 +0800 CST

Unable to change desktop environment with Lightdm in Ubuntu 20.10

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I just shifted to Ubuntu Mate 20.10. I prefer to use i3 as my window manager. However I am unable to login into i3 through lightdm!

Even if I select i3 from the gear icon on the login screen, it keeps logging into Mate. It's been frustrating.

I tried the obvious

sudo dpkg-reconfigure lightdm

but that doesn't work!

So I suspect some config file in usr/share/lightdm or .dmrc is to be blamed for this behavior! I have tried tinkering around and changed mate to i3 on some of these files. But it has not worked so far!

Please help.

p.s.: just-venting-out: Why do Distros do this?! :(

lightdm

1 Answers

  1. I can confirm the discovered behavior on fresh Ubuntu MATE 20.10 VM.
    I have reported bug 1910279 to LaunchPad.

    As a workaround you have to remove Arctica Greeter by:

    sudo apt autopurge arctica-greeter

    then install Slick Greeter back with

    sudo apt-get install slick-greeter

    then apply green MATE theme from Ubuntu MATE 20.04 LTS to it by executing long single command

    cat <<EOF | sudo tee /usr/share/glib-2.0/schemas/31_ubuntu-mate.gschema.override
[x.dm.slick-greeter]
background='/usr/share/backgrounds/ubuntu-mate-common/Green-Wall-Logo.png'
background-color='#3C3B37'
draw-grid=false
draw-user-backgrounds=false
enable-hidpi='auto'
font-name='Ubuntu 11'
icon-theme-name='Ambiant-MATE'
high-contrast=false
show-hostname=true
#logo=Logo file to use
onscreen-keyboard=false
#other-monitors-logo=Logo file to use for other monitors
# play-ready-sound=A sound file to play when the greeter is ready
screen-reader=false
show-power=true
show-a11y=true
show-keyboard=true
show-clock=true
show-quit=true
theme-name='Ambiant-MATE'
xft-antialias=true
xft-dpi=96
xft-hintstyle='hintslight'
xft-rgba='rgb'
EOF
sudo glib-compile-schemas /usr/share/glib-2.0/schemas

    then reboot and login to i3 session.

    Also I would recommend to revert all manual changes, which you have done.
    All system files are controlled by APT and your method is incorrect.

    Notes:

    1. to revert the above customization use sudo rm /usr/share/glib-2.0/schemas/31_ubuntu-mate.gschema.override; sudo glib-compile-schemas /usr/share/glib-2.0/schemas ; sudo apt-get install arctica-greeter.
    2. for longer support and to decrease number of surprises I would recommend to install Ubuntu MATE 20.04 LTS with 5-year support instead of 9-months-supported 20.10.
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