Just got a fresh Linux mint 19.2 installed, i needed docker so i went to the docker doc and followed the process.
https://docs.docker.com/install/linux/docker-ce/ubuntu/
everything went well until step 4 of the repository set up.
on the 4 step it says "Malformed input, repository not added."
I've changed "$(lsb_release -cs)" to "tina" and "tara" still doesn't work.
the 4th step to set up the repository:
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo nano /etc/apt/sources.list.d/additional-repositories.list
add the following line in the file
deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable
then,
sudo apt update
you know the rest of the steps. Good luck!