--force-confold and --force-confnew are options to dpkg that only control whether dpkg conffile prompts are shown. pam configuration files are not conffiles, because conffiles are not a suitable mechanism for managing files with multiple sources of configuration data.
The whiptail prompts are done through debconf, which means that a DEBIAN_FRONTEND=none setting will give you the desired results for a non-interactive upgrade. ** Changed in: pam (Ubuntu) Status: New => Won't Fix -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to pam in Ubuntu. https://bugs.launchpad.net/bugs/1480902 Title: pam-auth-update ignores force-confdef and force-confold when configuring Status in pam package in Ubuntu: Won't Fix Bug description: When the libpam-systemd package is installed, the apt settings "force- confdef" and "force-confold" are ignored, so that any of the "/etc/pam.d/common-*" are modified, the whiptail menu is shown; this breaks unattended system upgrades. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: libpam-systemd 204-5ubuntu20.13 ProcVersionSignature: Ubuntu 3.19.0-25.26~14.04.1-generic 3.19.8-ckt2 Uname: Linux 3.19.0-25-generic x86_64 NonfreeKernelModules: zfs zunicode zcommon znvpair zavl ApportVersion: 2.14.1-0ubuntu3.11 Architecture: amd64 CurrentDesktop: XFCE Date: Mon Aug 3 14:20:58 2015 EcryptfsInUse: Yes InstallationDate: Installed on 2015-07-30 (3 days ago) InstallationMedia: Xubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1) SourcePackage: systemd UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pam/+bug/1480902/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp