systemd documentation [1] recommends to use the directory /usr/share/factory/etc as a "Repository for vendor-supplied default configuration files. This directory should be populated with pristine vendor versions of all configuration files that may be placed in /etc. This is useful to compare the local configuration of a system with vendor defaults and to populate the local configuration with defaults."

In this case, "vendor" means Arch Linux. Most of those "vendor-supplied default configuration files" come from the filesystem package, so I would consider it appropriate to install a copy of these to /usr/share/factory/etc, for the reasons described in the quote from above.

Currently, my /usr/share/factory/etc only contains some stuff installed by systemd:

$ find /usr/share/factory/etc -exec pacman -Qo {} +
/usr/share/factory/etc/ is owned by systemd 232-7
/usr/share/factory/etc/pam.d/ is owned by systemd 232-7
/usr/share/factory/etc/pam.d/other is owned by systemd 232-7
/usr/share/factory/etc/pam.d/system-auth is owned by systemd 232-7
/usr/share/factory/etc/nsswitch.conf is owned by systemd 232-7

And this is really bad: /etc/nsswitch.conf and /etc/pam.d/{other,system-auth} are installed by different packages (filesystem and pambase, respectively), but with completely different contents. This should be cleaned up, so that users can rely on the expectation set by systemd's documentation (which is also installed as the authoritative-looking file-hierarchy(7) manpage).

The concrete use-case that provoked me to file this task was that I plan to write an audit tool for the users and groups that are present on my systems, and I would like to have a base against which to diff. Sure, I could `tar xf /var/cache/pacman/pkg/filesystem-$(pacman -Q filesystem | cut -d' ' -f2)-x86_64.pkg.tar.xz`, but that's plain ugly and relies on the existence of a package cache. It would be much nicer if I had /usr/share/factory/etc/{group,gshadow,passwd,shadow} at my disposal.

[1] https://www.freedesktop.org/software/systemd/man/file-hierarchy.html