Ubuntu/APT

add-apt-repository

# 1. Install the tool if needed (for older systems)
sudo apt install software-properties-common

# 2. Add the repository (replace ppa:user/repo or deb URL with the actual one)
sudo add-apt-repository ppa:user/repo  # For Launchpad PPAs
# OR
sudo add-apt-repository 'deb [arch=amd64] http://repo.address/ubuntu focal main' # For direct deb lines

# 3. (Optional) Fetch GPG Key if not handled automatically
# wget -qO - https://repo.address/key.gpg | sudo gpg --dearmor -o /usr/share/keyrings/repo-keyring.gpg

# 4. Update your package list
sudo apt update