Cannot set APT::Periodic::Update-Package-Lists

[Benjamin Portner]

On Ubuntu 22.04.4 running apt 2.4.11 (amd64), I cannot set APT::Periodic::Update-Package-Lists. No matter which value I enter, it is always interpreted as '1'. Steps to reproduce:

1. Open /etc/apt/apt.conf.d/10periodic
2. Enter APT::Periodic::Update-Package-Lists "2" (or any other number, or "3h" or "always")
3. Save and exit
4. Run sudo apt-config shell UpdateInterval APT::Periodic::Update-Package-Lists
5. The console prints UpdateInterval='1'

Changing other config options, like APT::Periodic::Download-Upgradable-Packages, works. Changing the order of the lines in 10periodic does not affect the result.

[Julian Andres Klode (juliank)]

You probably have /etc/apt/apt.conf.d/20auto-upgrades or another file later in the search order that overrides the setting, 20auto-upgrades is what unattended-upgrades configures.

[Benjamin Portner (benportner)]

Bingo! 20auto-upgrades was the cause. Thanks for the fast support!