lubuntu 18.04 remove old packages after auto-upgrade to lubuntu 20.04 (cleanup)

remove-remaining-packages -from-lubuntu-1804-after-upgrade.md

remove remaining lubuntu lxdm components

remove remaining lubuntu lxdm components after auto-upgrading from 18.04 to 20.04 version (it is unsupported, but if it happened to you, cleanup your system, remove unneeded duplicate applications)

make sure we are up to date

just in case, you never know

sudo apt update && sudo apt full-upgrade -y
sudo do-release-upgrade

check diskspace

df -H

remove a bunch of outdated packages from the lxde era

sudo apt purge leafpad file-roller galculator gpicview xpad xfburn simple-scan mtpaint pidgin sylpheed transmission-gtk abiword evince gnumeric audacious gnome-mpv guvcview pcmanfm gdebi lxterminal hardinfo lightdm lxpanel lxsession obconf gnome-software gnome-disk-utility system-config-printer-gnome lxhotkey-gtk synaptic update-manager lxpolkit lxtask lxshortcut blueman usb-creator-gtk evince-common
# if you enabled the hardware enablement stack for 18.04, remove also (not needed anymore)
sudo apt purge linux-image-generic-hwe-18.04
sudo apt purge linux-headers-generic-hwe-18.04
sudo apt autoremove

cleanup folders that could not be autoremoved

cd /etc/xdg/pcmanfm
sudo rm lubuntu -rf
cd /etc
sudo rm pcmanfm -rf
sudo reboot

optional, if you are unsure or if things do not work

if not everything is as expected, juts remove the lubunutu desktop packages and reinstall again. note that your system then only boots to the commandline, until after you reinstall the desktop packages

## remove all of lubuntu (grapical)
sudo apt remove lubuntu-desktop
sudo apt autoremove
# make sure your system boots to the cli (after we removed the gui)
sudo systemctl isolate multiuser.target
sudo systemctl set-default multiuser.target
sync
sudo reboot

remove lightdm (if stil present)

sudo apt remove lxgreeter
sudo apt remove lightdm
sudo apt remove lightdm-greeter
sudo apt-get purge lightdm
sudo apt-get install sddm

see what the default dm is now

cat /etc/X11/default-display-manager
sudo dpkg-reconfigure sddm

reinstall lubuntu-desktop and vim

sudo apt install lubuntu-desktop
sudo apt install vim-athena  --install-suggests
sync
sudo reboot

check for the default dm in use

# set it to sddm if not already so
sddm-greeter --test-mode
sudo update-alternatives  --config sddm-ubuntu-theme
# you should see that ssdm is used
cat /etc/X11/default-display-manager 
# check and set what to enable at boot time (we want a gui now)
systemctl get-default
sudo systemctl isolate graphical.target
sudo systemctl set-default graphical.target
sudo reboot