Memory Matrix

Many distributions do not provide a source ISO to match their installation media. Debian provides one, as does Oracle. As far as I know, those are the only two that do that. Since the GPL requires one to redistribute the source code with the program, one needs to possess a copy of that source code if they want to redistribute code later on. This matters because internet archives may vanish as projects change. Old distributions may no longer have source code available online. As projects place everything on GIT servers rather than offering easily mirrored source archives, it becomes less likely that folks will mirror that source over time. To that end, here is how to create a source set to mirror the installation media for a .deb based distribution.

Mount the installation media. Create a directory to contain the source files and cd into that directory on a terminal. Assuming that the mount point is /media/user/DEVUAN611, run the following command:
find "/media/user/DEVUAN611"/ -name "*.deb" -type f -exec sh -cvx 'apt-get source $(dpkg-deb -f "$0" Package)' {} \;
This will identify each .deb file on the media and download the corresponding source .deb file. Save the downloaded source as an ISO via Brasero or other tool and you now have a matching source ISO for the installation media in case you want to redistribute that software a decade or more hence.