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 anotherapt-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
- Add key with
apt-key
- Install in terminal with
apt-get
- Search in dash
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.