Linux · System Config, Time & Hardware

Running ls -l /dev/sda1 shows a b where a file size normally sits — what does that tell you, and how do block and character devices differ?

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 System Config, Time & Hardware

On Debian or Ubuntu you need a different keyboard layout — which file holds it, and why is editing that file directly the wrong first move?

During install you want to name the machine but pick localhost — why is that the one hostname to never choose?

A distro ships with its default firewall on and you set up an SSH server — clients still can't reach it. What is the firewall doing and what fixes it?

Which boot loader does nearly every Linux distribution install by default, and where does it typically go?

Coming from Windows, an admin reflexively reboots after editing a config file. When is a reboot actually required on Linux, and what do you do instead?

Where do almost all Linux configuration files live, and how are the files of larger programs kept from cluttering that directory?

Start learning today

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