APT-offline came in handy when I was creating my MX-Linux 25.1 installation. I wanted to experiment with adding Audacity, because it seemed to cause instability when I recently added it to an MX-L 23.3 installation. So, I didn't want to install it on my initial (full) installation on an SSD, because if it caused instability, I might not be able to "undo" it completely without creating a new installation without Audacity.
So, I decided to install everything (including APT-Offline) except Audacity on the full installation, then turn the full installation into an ISO (using the Snapshot tool), create a nonpersistent live installation from the ISO, boot the live installation, and add Audacity to the resulting live session. This required me to install a package index on the live installation, which requires a 90MB download. But if the PC shut down after installing the package index, the package index would be lost and I'd have to download it all over again.
But by using APT-offline, I could download the package index to a flash drive, and then install it on the live session from the flash drive, to avoid the possibility of having to download it all over again. If APT-Offline were installed on MX-Linux by default, I could have downloaded the package index once and installed it on the full installation as well. But I had to install the package index on the full installation before I could install APT-offline. [1]
So I created the aforementioned Snapshot-ISO, turned it into a live installation, booted it, and used APT-Offline to download and install the package index, and then Audacity. So far, there have been no indications that Audacity causes any instability.
Although I hadn't used APT-offline in a long time, it didn't take long to get the hang of it again, thanks to my system which allows me to use the same simple get- and install-commands for everything (I use the GUI to perform the set-op, i.e. to generate signature files).
It's normal to get a lot of error messages when using APT-Offline to download stuff, because there are two systems for organizing the servers, and signature files have to be prepared for either case. So, the error messages just mean that the URLs to which the error messages apply don't exist on the chosen server. If the same signature file were used on a server with the other organization, the error messages would apply to the other URLs. I just ignore the error messages and have always obtained the required files.
Notes
[1] There are ways to install APT-Offline without first installing the package index, as explained elsewhere in this blog. But they're a PITA, especially if the PC has no internet connection, which is why APT-offline was created. By not including it by default, its purpose, which is to make it convenient to install stuff without an internet connection, is defeated.
