Linux · Package Management: APT & dpkg

You mis-answered the Postfix mail server's setup questions during install. Since Debian ran those config scripts automatically at install time, how do you get them back?

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More in Package Management: APT & dpkg

You run apt install right after a fresh Debian install and it keeps prompting you to reinsert the installation DVD instead of downloading from the internet. What causes this and how do you fix it?

On Debian, the default sources.list only enables free packages, but you need the proprietary NVIDIA driver. What must you add to the source lines first?

On Fedora, why is running dnf update in the terminal often preferable to using the graphical Software Update, especially for a first big update?

On Fedora the SSH server is installed but the daemon isn't running after boot. What single command both enables it at boot and starts it now?

Fresh Fedora and openSUSE installs can't play many audio/video formats and lack the NVIDIA driver. What kind of source fixes this, and what is each distro's most popular one?

Arch and Manjaro don't use apt or dnf. What command handles package management there, and what extra GUI does Manjaro ship?

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