How to set proxy with environment variables `http_proxy` and `https_proxy` in a raw terminal environment?

I am using clash for proxy. But when installing Nixos from a raw terminal(the minimal NixOS ISO), there is no clash or anything installed. Also, due to network issue (that’s why I need a proxy), I can’t download anything. The only thing I have is a subscription URL and many proxy services info fetched from the URL. Then, how to use these to make a proxy so that I can get internet access through proxy in the raw terminal?

I know the common answer is setting http_proxy or https_proxy in such format: http://<proxy_host>:<proxy_port> or http://<name>:<password>@<proxy_host>:<proxy_port> .

The question is, with a specifically selected proxy server, if using "http://<proxy_host>:<proxy_port>", then the response is curl: (52) Empty reply from server from curl If taking the latter format, I wonder what the name and password should be.

see NixOS Search

Thanks for your attention. But the doc there only tells the format of these env variables, which I did know.
Generally, if using a proxy app, I would use the format like http://<LOCALHOST>:<proxy_port>. But in my case here, there is no proxy app.

First, please check if this manual section would help. If it doesn’t work in your situation, you can install NixOS from an existing Linux distribution where clash is already available, or build a NixOS ISO with clash in systemPackages.