It is not every day that I have to set up a fresh install of Ubuntu, and I end up forgetting and having to repeat research on specific “tweaks”. I am now using this page as my own reference.

• systemd-networkd
  • tired of those 120s boot delays while the network waits for DHCP?
  • following this fix:
    • sudo systemctl disable systemd-networkd-wait-online.service
    • sudo systemctl mask systemd-networkd-wait-online.service
  • also mark all unneeded interfaces as optional e.g. in /etc/netplan/nn-whatever.yaml:
    
  • to find out which services are impacted:
    • sudo systemctl show -p WantedBy network-online.target

• repository maintenance
  • upgrading from old versions may have “remnant” repositories lurking around
    • show the what is in the encoded /etc/apt/trusted.gpg file: apt-key --list
      • manually remove individual entries (using the fingerprint): apt-key del "xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx"
    • check the sources in /etc/apt/sources.list.d
    • check the trusted sources in /etc/apt/trusted.gpg.d
    • check sources in /etc/apt/sources.list:
      • show what is in /etc/apt/sources.list: add-apt-repository --list
      • manually remove individual entries (using entire line): add-apt-repository --remove "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main"

• fix broken/partial/stuck package installs
  • try any of the following in order:
    • sudo dpkg --configure -a
    • sudo apt-get install -f
    • delete pending actions: sudo rm -fr /var/lib/dpkg/updates/*