Preserving locally modified configuration files - Dpkg::Options --force-confdef & --force-confold not working on command line

[Jaikumar Sharma]

Hi,

In debian 9.13 server, i'm using custom configuration (locally modified)
file /etc/samba/smb.conf , I do not want to upgrade this file and retain
the old configuration file without prompting during automatic upgrades  but
it is still giving me the prompt even after specifying on command line :

sudo apt-get dist-upgrade -o Dpkg::Options::=--force-confdef -o
Dpkg::Options::=--force-confold -y --allow-unauthenticated

Still prompt/complain about locally modified configuration file, as per
documentation it should work.

and

I've also tried to put these below command in a config file under
/etc/apt/apt.conf.d/50-unattended-upgrades :

Dpkg::Options {
  "--force-confdef";
 "--force-confold";
}

but behaviour is the same in both cases.

Does somebody know what may be wrong here? or i'm doing it wrong?

Thank you.
Regards,
Jaikumar