UPDATE_CMAKE.md

A-1. Uninstall the default version provided by Ubuntu's package manager and configuration by using:

sudo apt remove --purge --auto-remove cmake

or:

sudo apt purge --auto-remove cmake

A-2. Prepare for installation

sudo apt update && \
sudo apt install -y software-properties-common lsb-release && \
sudo apt clean all

A-3. Obtain a copy of kitware's signing key.

wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | sudo tee /etc/apt/trusted.gpg.d/kitware.gpg >/dev/null

A-4. Add kitware's repository to your sources list for Ubuntu Focal Fossa (20.04), Ubuntu Bionic Beaver (18.04) and Ubuntu Xenial Xerus (16.04).

sudo apt-add-repository "deb https://apt.kitware.com/ubuntu/ $(lsb_release -cs) main"

A-5. As an optional step, is recommended that we also install the kitware-archive-keyring package to ensure that Kitware's keyring stays up to date as they rotate their keys.

sudo apt update
sudo apt install kitware-archive-keyring
sudo rm /etc/apt/trusted.gpg.d/kitware.gpg

A-6. Finally we can update and install the cmake package.

sudo apt update
sudo apt install cmake