Linux · Package Management: APT & dpkg

Two Java versions are installed, yet typing java always runs one specific version. What Debian-originated mechanism decides that, and how is it wired?

Answer locked. Get the free KnowCard app to reveal it — plus spaced-repetition review so it actually sticks.

This is one card from the KnowCard library — thousands more across SAP, Linux, Python and more. In the app you get the answer, AI explanations, and cards that come back right before you would forget them. Free to start on iOS, Android or the web.

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?

Start learning today

Free to start — download the app or use it in your browser.