How to add a GPG key to the apt sources keyring?

This a a one line command to enter in terminal. See What is a terminal and how do I open and use it?

To use it, you would paste the entire command in the terminal (remember to use https):

wget -qO - https://deb.opera.com/archive.key | sudo apt-key add -

But of course, it is daunting just copying and pasting commands without knowing what they are doing, and having no instructions on how to undo their actions, so here is a basic breakdown of the commands:

  • wget downloads something from a server. See wget manual for Ubuntu 16.04.
  • | is a pipline, which takes the output of one command and runs it into the input of another
  • apt-key add adds a package key

So it basically downloads the key and then adds it in one command.

I tested the command and it should work.

Now to verify that it worked, run this command (from this answer):

apt-key list

This will list the keys added and the key from Opera should be listed on the bottom like this:

pub   1024D/30C18A2B 2012-10-29 [expires: 2014-10-29]
uid                  Opera Software Archive Automatic Signing Key 2013 <[email protected]>
sub   4096g/C528FCA9 2012-10-29 [expires: 2014-10-29]

The linked answer also shows that you can remove the key if needed, using:

sudo apt-key del 30C18A2B

with 30C18A2B being the key-id from the list.

After performing that command, and setting up the sources exactly like in your screen-shot, do:

sudo apt-get update
sudo apt-get install opera

(note there are some random warnings, but nothing that affects the install or software center operations)

And for the removal (just in case): What is the correct way to completely remove an application?

So in summary:

  • Add repository enter image description here
  • Add key with apt-key
  • Install in terminal with apt-get
  • Search in dash enter image description here

If you are manually adding a key from a PPA, use

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 00000000

Replacing the 00000000 with the second part of the key informed in the PPA website that you want to add.

For example, if you find this line:

 4096R/7BF576066

Use only the second part (no matter its size), which in this example is 7BF576066


Newer versions of apt also support the following:

apt-key adv --fetch-keys http://deb.opera.com/archive.key

This method also provides more detailed feedback as well, e.g.:

gpg: key 7BD9BF62: public key "signing key <[email protected]>" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

This also has the added bonus of removing the need for additional dependencies like wget or curl.

Tags:

Gnupg

Apt

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