/etc/apt/apt.conf.d/ priority - overrule configuration file?

The folder

/etc/apt/apt.conf.d/

contains lots of files.

01autoremove
10periodic
15update-stamp
20archive
20dbus
20packagekit
50unattended-upgrades
70debconf
99synaptic
99update-notifier

What are those 01, 10, ..., 99 numbers all about?

Do they imply "read 01 first, read 99 last and let 99 overrule settings made in earlier numbers"?

Let's for example say there is only one setting in 50unattended-upgrades, where I want to overrule the default setting with my own preference.

I could edit 50unattended-upgrades directly, but then it becomes messy if the maintainer updates that file - I have to merge the changes.

Could I also create 51unattended-upgrades with just the single value I prefer and therefore overrule the default in 50unattended-upgrades?

Solution 1:

Source: http://debian-handbook.info/browse/wheezy/sect.apt-get.html

Directories ending in .d

Directories with a .d suffix are used more and more often. Each directory represents a configuration file which is split over multiple files. In this sense, all of the files in /etc/apt/apt.conf.d/ are instructions for the configuration of APT. APT includes them in alphabetical order, so that the last ones can modify a configuration element defined in one of the first ones.

For example 60unattended-upgrades should overrule 50unattended-upgrades.