apt_automation

export DEBIAN_FRONTEND=noninteractive

Suppress confirmation prompts using 'apt -y'

Conffile differences:
--force-confdef
--force-confold
--force-confnew
Apply these using -o

If the package requires information it's possible to preseed debconf:
Need the package name, the confdb key, and type of answer.
echo <package> <key> <value> | debconf-set-selections

Can do this for license acceptance. Necessary for automation of template
builds, which otherwise fail if input is required.
For example, firmware-ipw2x00 requires acceptance of license before
installation.
apt download firmware-ipw2x00 
ar x firmware-ipw2x00_20161130-4_all.deb
tar zxf control.tar.gz
The key can be found in preinst in the check:
db_get firmware-ipw2x00/license/accepted

(Alternatively install package in qube, and use debconf-get-selections to
find the relevant keys)

In template building:
  chroot_cmd sh -c 'echo "debconf firmware-ipw2x00/license/accepted select true" | debconf-set-selections'
  aptInstall firmware-ipw2x00