how to check if APT is already exist in ubuntu

Question

I'm creating a bash script to for installing docker compose. and first i want to check first if the docker already in the sources.list so i will not append again. how can i achieve this?

Answer 1

For a current Debian or Ubuntu, there should already be a directory /etc/apt/sources.list.d. So my idea would be to just create a file there, put the repo in, and check for the file existance.

Like:

apt_src_file="/etc/apt/sources.list.d/docker.list"

# File exists?
if [ -f "$apt_src_file" ]; then
    echo "already installed"
    # Quit script here. If you do not want to quit, you need an ELSE section...
    exit 0
fi

# Insert source into file
echo "deb ........." > $apt_src_file

That's way easier to handle as a fulltext-search...

PS: Please NEVER paste an image to so, when plain text will do! ALWAYS copy the code!