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Asked: 2026-05-18T00:16:19+00:00

How would I change a pixel on a display, in C? Assume NOTHING: I

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How would I change a pixel on a display, in C?

Assume NOTHING: I am using a linux machine from console to do this. I do not want to use GUI toolkits or frameworks to draw the pixel. I do not want to draw the pixel in a window. I want to draw the pixel directly to the screen.

EDIT: I have a screen. I’m on a laptop running linux from console. I’d prefer a solution not using X as I’d rather learn how X works than how to use X.

If theres more information, ask, but don’t assume. I’m not trying to build a GUI, and that was the main purpose of blocking assumptions as I don’t want people to assume I’m doing things the long way when in reality I’m just tinkering.

EDIT 2: You may use any X11 related libraries provided that you can explain how they work.

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  1. Editorial Team

    If we really assume nothing, can we even assume that X is running? For that matter, can we even assume that there is a video card? Perhaps Linux is running headless and we’re accessing it over a serial console.

    If we are allowed to assume a few things, let’s assume that Linux has booted with framebuffer support. (It’s been a couple years since I worked with Linux framebuffers, I may get some of the details wrong.) There will be a device created, probably /dev/fb or /dev/fb0. Open that file and start writing RGB values at an offset, and the screen will change, pretty much regardless of anything: text console, graphical console, full-fledged desktop envrionment, etc. If you want to see if framebuffer support is working, do dd if=/dev/zero of=/dev/fb on the command line, and the display should go all black.

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