How to check if gpg key already exist with bash then skip downloading/adding?

Question

So basically, I want to run these 2 commands but I want to check if the keys already existed. I know how to do the ifthenelse in bash but I'm not sure how to get the result and store in variable for me to check so that i can put it in the conditional operator. For example, if it already existed then I can skip downloading and adding it again.

Example 1 (--fetch-keys):

    sudo apt-key adv --fetch-keys https://packages.microsoft.com/keys/microsoft.asc
sudo tee /etc/apt/sources.list.d/vscode.list > /dev/null <<- END
    deb [arch=amd64] https://packages.microsoft.com/repos/vscode stable main
END

Example 2 (--recv-keys):

    sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys B9A06DE3
sudo tee /etc/apt/sources.list.d/inkscape.list > /dev/null <<- END
    deb [arch=amd64] http://ppa.launchpad.net/inkscape.dev/stable-daily/ubuntu bionic main
END

Answer 1

How about something like:

TEST=$(apt-key list 2> /dev/null | grep my_app_name)
if [[ ! $TEST ]]; then
    echo "Missing - need to run --fetch-keys or --recv-keys"
fi

I piped stderr into the null device ( 2> /dev/null ) to hide the warning you get for using apt-key list in a script.

Try running "sudo apt-key list" on its own so you can see what the output looks like, in case you want to change the "grep" to be more selective.

Answer 2

You could save each key in its own file and test if the file exist.

keyring=/etc/apt/trusted.gpg.d/inkscape.gpg
if [ ! -f $keyring ]; then
  sudo apt-key --keyring $keyring \
    adv --keyserver keyserver.ubuntu.com --recv-keys B9A06DE3
fi
sudo tee /etc/apt/sources.list.d/inkscape.list > /dev/null <<- END
deb [arch=amd64] http://ppa.launchpad.net/inkscape.dev/stable-daily/ubuntu bionic main
END

Answer 3

the command 'apt-key list' may not list all the keys you already have, in that case 'grep' would not inform you that a key exists.

if you imported a key using 'gpg --import', then 'gpg --list-keys' followed by a grep would inform you if the key exists or not. for example

gpg --list-keys | grep zoom 
if [[ $? -ne 0 ]]; then
  wget https://zoom.us/linux/download/pubkey?version=5-12-6
  gpg --import  pubkey?version=5-12-6
fi