Ubuntu tips and tricks

How to cleanly remove x11

sudo apt purge 'x11-*'
sudo apt autoremove

apt-get update “the following signatures couldn’t be verified because the public key is not available”

$ sudo apt update
Err:5 https://packages.cloud.google.com/apt kubernetes-xenial InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
  
#need to add the missing Key B53DC80D13EDEF05
$sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys B53DC80D13EDEF05
Executing: /tmp/apt-key-gpghome.xfmtcCbrXz/gpg.1.sh --keyserver keyserver.ubuntu.com --recv-keys B53DC80D13EDEF05
gpg: key B53DC80D13EDEF05: 1 duplicate signature removed
gpg: key B53DC80D13EDEF05: public key "Rapture Automatic Signing Key (cloud-rapture-signing-key-2022-03-07-08_01_01.pub)" imported
gpg: Total number processed: 1
gpg:               imported: 1

#now update will be successful