Updating Flatpack applications on Linux Mint 19

Since upgrading to Linux Mint 19, I have installed some software from Flatpack. The cause for my curiosity was that you could have the latest versions of applications like GIMP or Libreoffice without having to depend on a third-party PPA. Installation is straightforward given the support built into Linux Mint. You just need to download the relevant package from the Flatpack website and running the file through the GUI installer. Because the packages come with extras to ensure cross-compatibility, more disk space is used but there is no added system overhead beyond that from what I have seen. Updating should be as easy as running the following single command too:

flatpack update

However, I needed to do a little extra work before this was possible. The first step was to update the configuration file at ~/.local/share/flatpak/repo/config to add the following lines:

[remote "flathub"]
gpg-verify=true
gpg-verify-summary=true
url=https://flathub.org/repo/
xa.title=Flathub

Once that was completed, I ran the following commands to import the required GPG key:

wget https://flathub.org/repo/flathub.gpg
flatpak --user remote-modify --gpg-import=flathub.gpg flathub

With this complete, I was able to run the update process and update any applications as necessary. After that first run, it has been integrated in to my normal processes by adding the command to the relevant alias definition.