I'm using Ubuntu 18.04 and I'm automating the installation of a Debian package via apt install.

This package requires me to review a license agreement and choose to accept or deny it, and I learned I can use "preseeding" to automate this process which is talked about in "Appendix B. Automating the installation using preseeding".

The section "B.3. Creating a preconfiguration file" said the following about the Owners field:

For debconf variables (templates) used only in the installer itself, the owner should be set to “d-i”; to preseed variables used in the installed system, the name of the package that contains the corresponding debconf template should be used. Only variables that have their owner set to something other than "d-i" will be propagated to the debconf database for the installed system.

My questions are:

  1. What is the difference between an "installer" and an "installed system"?
  2. I am using apt to install this package. Is this the "installer" case?
  3. What is the debconf database? From what I've learned so far, it is the file /var/cache/debconf/config.dat. Am I right?
  4. The last sentence of "...'d-i' will be propagated to the debconf database for the installed system" makes me feel that if I use apt to install a package and use d-i in the preseed file, the config.dat file would not be changed by my installation. But after I ran debconf-set-selections <my-preseed-file>, I found the config.dat file was changed. So I'm confused by what exactly this part of document means.

Thanks for the help!

  • 1
    Most of your confusion would be cleared up if you note that the document you're reading is for automating an installation of Ubuntu itself, not just some package. The installation of Ubuntu of course includes installation of packages, but it also includes other things (e.g., disk partitioning, account creation, etc.). – muru Jun 4 at 3:42
  • @muru I actually noticed that but I still haven't figured out how that "d-i" affects the behavior, and I guess it's partly because the documentation didn't explain the difference between an "installer" and an "installed system" (or maybe it's explained elsewhere that I am not aware of). – yaobin Jun 4 at 18:21

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