Configure Apt Sources for Updates in Debian

How to configure apt sources for updates in Debian 11 (Bullseye). Configure apt sources.list repositories, update the package database and install the latest updates on your server.

Apt (Advanced Packaging Tool)

The Debian package manager Apt is used to download and install software from repositories/sources.

Apt is configured using the sources.list file

/etc/apt/sources.list

Default apt sources.list

Edit apt sources.list

Edit the apt sources.list and make these changes: comment out the line for the cdrom source, add contrib and non-free repositories.

nano /etc/apt/sources.list

# deb cdrom:[Debian GNU/Linux 11.0.0 _Bullseye_ - Official amd64 DVD Binary-1 20210814-10:04]/ bullseye contrib main
# deb cdrom:[Debian GNU/Linux 11.0.0 _Bullseye_ - Official amd64 DVD Binary-1 20210814-10:04]/ bullseye contrib main

deb http://deb.debian.org/debian/ bullseye main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye main contrib non-free

deb http://security.debian.org/debian-security bullseye-security main contrib non-free
deb-src http://security.debian.org/debian-security bullseye-security main contrib non-free

# bullseye-updates, to get updates before a point release is made;
# see https://www.debian.org/doc/manuals/debian-reference/ch02.en.html#_updates_and_backports
deb http://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye-updates main contrib non-free 

Your updated sources.list should look like this

Update the package database

apt-get update

Install the latest updates

apt-get upgrade

Reference:

Debian SourcesList
https://wiki.debian.org/SourcesList

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