Add GPG keys to the APT keyring
Add a GPG key by key ID from the default keyserver
sudo add-apt-key [KEY_ID]
Add a GPG key from a specific keyserver
sudo add-apt-key -k [keyserver.ubuntu.com] [KEY_ID]
Add a key with verbose output
sudo add-apt-key -v [KEY_ID]
add-apt-key [options] keyid
add-apt-key requests the specified GPG key from a public keyserver and inserts it into the APT keyring so that archives signed with that key will be trusted. The default keyserver can be configured in /etc/default/add-apt-key.
-h, --help
Show usage information.
-v, --verbose
Verbose mode; show each command before it is executed.
-k, --keyserver name
Select a specific keyserver to use.
keyid
The GPG key identifier to add.
0 - Key was added successfully.
1 - Invalid arguments.
2 - GPG key ID cannot be retrieved or is malformed.
3 - Failure inserting key into APT keyring.
This tool may not be available on all distributions. The modern approach is to place repository keys in /etc/apt/keyrings/ and reference them directly in source list files with the signed-by option.