remove path https //dl.yarnpkg.com/debian in linux code example
Example 1: problem installing yarn ubuntu
sudo apt remove cmdtest
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
sudo apt update
sudo apt install yarn
Example 2: ubuntu install yarn
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list