Wondering how to delete Repository And GPG Key In Ubuntu? We can help you.

Ubuntu has four official repositories namely Main, Universe, Restricted, and Multiverse. A repository (repo) is a central place where the developers keep the software packages.

Using the repository keys, we can ensure that we are getting the packages from the right person. However, sometimes we would like to delete a repository along with its GPG key when it’s no longer necessary in our ubuntu systems.

Here at Bobcares, we handle Ubuntu servers of our customers as a part of our Server Management Services.

Today let’s see how our Support Engineers delete the repository and GPG key in Ubuntu.

How to delete repository and GPG key in Ubuntu – Steps to follow

We will see the steps that our Support Engineers follow for deleting the repository and key in Ubuntu.

Deleting a repository in Ubuntu

When we add a repository using ‘add-apt-repository’ command, it will be stored in /etc/apt/sources.list file.

For deleting a software repository from Ubuntu and its derivatives we do the following:

First, open the /etc/apt/sources.list file and look for the repository entry.

We can do this using the following command:

$ sudo nano /etc/apt/sources.list

And simply remove the entry to delete the repository.

After that, we can save and close the file.

However, if we have added PPA repositories, we must look into /etc/apt/sources.list.d/ directory and delete the respective entry.

Alternatively, we can delete the repository using ‘add-apt-repository’ command.

For example, we can delete the Systemback repository using the following command:

$ sudo add-apt-repository -r ppa:nemh/systemback

Finally, update the software sources list using the following command:

$ sudo apt update

Listing Repository keys

‘apt-key’ is used to manage the list of keys used by ‘apt’ to authenticate packages.

Following are the paths where trusted keys are found:

/etc/apt/trusted.gpg – Keyring of local trusted keys; new keys will be added here.
/etc/apt/trusted.gpg.d/ – File fragments for the trusted keys; additional keyrings can be stored here.

We can use the following command to list trusted keys with fingerprints:

$ sudo apt-key list

/etc/apt/trusted.gpg
--------------------
pub rsa4096 2017-12-15 [SCEA]
0A0F AB86 0D48 5603 32EF B581 B754 42BB DE9E 3B09
uid [ unknown] https://packagecloud.io/AtomEditor/atom (https://packagecloud.io/docs#gpg_signing) support@packagecloud.io
sub rsa4096 2017-12-15 [SEA]

pub rsa4096 2016-04-22 [SC]
B9F8 D658 297A F3EF C18D 5CDF A2F6 83C5 2980 AECF
uid [ unknown] Oracle Corporation (VirtualBox archive signing key) info@virtualbox.org
sub rsa4096 2016-04-22 [E]

pub dsa1024 2007-03-08 [SC]
4CCA 1EAF 950C EE4A B839 76DC A040 830F 7FAC 5991
uid [ unknown] Google, Inc. Linux Package Signing Key linux-packages-keymaster@google.com
sub elg2048 2007-03-08 [E]

pub rsa4096 2016-04-12 [SC]
EB4C 1BFD 4F04 2F6D DDCC EC91 7721 F63B D38B 4796
uid [ unknown] Google Inc. (Linux Packages Signing Authority) linux-packages-keymaster@google.com
sub rsa4096 2019-07-22 [S] [expires: 2022-07-21]

/etc/apt/trusted.gpg.d/numix_ubuntu_ppa.gpg
-------------------------------------------
pub rsa1024 2013-08-13 [SC]
43E0 7612 1739 DEE5 FB96 BBED 52B7 0972 0F16 4EEB
uid [ unknown] Launchpad PPA for Numix Maintainers

/etc/apt/trusted.gpg.d/snwh_ubuntu_ppa.gpg
------------------------------------------
pub rsa1024 2012-06-27 [SC]
D320 D0C3 0B02 E64C 5B2B B274 3766 2239 8999 3A70
uid [ unknown] Launchpad PPA for Sam Hewitt

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
790B C727 7767 219C 42C8 6F93 3B4F E6AC C0B2 1F32
uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) ftpmaster@ubuntu.com

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092
uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) cdimage@ubuntu.com

/etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg
------------------------------------------------------
pub rsa4096 2018-09-17 [SC]
F6EC B376 2474 EDA9 D21B 7022 8719 20D1 991B C93C
uid [ unknown] Ubuntu Archive Automatic Signing Key (2018) ftpmaster@ubuntu.com

Delete repository keys in Ubuntu

We use “apt-key” command to add the repository keys.

First, we will list the added keys using the following command:

$ sudo apt-key list

This command will list all added repository keys.

/etc/apt/trusted.gpg
--------------------
pub rsa1024 2010-10-31 [SC]
3820 03C2 C8B7 B4AB 813E 915B 14E4 9429 73C6 2A1B
uid [ unknown] Launchpad PPA for Kendek

pub rsa4096 2016-04-22 [SC]
B9F8 D658 297A F3EF C18D 5CDF A2F6 83C5 2980 AECF
uid [ unknown] Oracle Corporation (VirtualBox archive signing key) <info@virtualbox.org>
sub rsa4096 2016-04-22 [E]

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-archive.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
790B C727 7767 219C 42C8 6F93 3B4F E6AC C0B2 1F32
uid [ unknown] Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub rsa4096 2012-05-11 [SC]
8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092
uid [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>

/etc/apt/trusted.gpg.d/ubuntu-keyring-2018-archive.gpg
------------------------------------------------------
pub rsa4096 2018-09-17 [SC]
F6EC B376 2474 EDA9 D21B 7022 8719 20D1 991B C93C
uid [ unknown] Ubuntu Archive Automatic Signing Key (2018) <ftpmaster@ubuntu.com>

From the above output, the long (40 characters) hex value is the repository key.

If we want the APT package manager to stop trusting the key we can delete it using the following command:

$ sudo apt-key del "3820 03C2 C8B7 B4AB 813E 915B 14E4 9429 73C6 2A1B"

Or, we can alternatively specify the last 8 characters:

$ sudo apt-key del 73C62A1B

Finally, we can run the following command to update the repository lists:

$ sudo apt update

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Conclusion

In short, we saw the steps that our Support Engineers follow to delete repository and GPG Key In Ubuntu.