/bin/debconf-set is in ubiquity 18.04.14.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 | #!/bin/sh
set -e
export DEBIAN_FRONTEND=noninteractive
. /usr/share/debconf/confmodule
db_set "$1" "$2"
|