✅ Solved

Closing this since it's a duplicate of #907

Someone actually already answered it: #907 (comment). I wasn't able to make it work at first because I was on Windows but running a .sh file. Which means it's actually still using the Linux/Mac bash syntax. That means I could've been using export instead of set when inside a bash file.

I've also updated my shell script like so:

# scripts/openapi-generate.sh

PUBLIC_API_URL=$(dotenv -p PUBLIC_API_URL)

# Arg$1: The public api url.
if [ -z "$PUBLIC_API_URL" ]; then
 echo "Please specify PUBLIC_API_URL in the .env file."
 exit 1
fi

echo "🔑 Disabling NODE_TLS_REJECT_UNAUTHORIZED to allow introspecting HTTPS API."
export NODE_TLS_REJECT_UNAUTHORIZED=0

openapi-typescript $PUBLIC_API_URL -o src/lib/types/openapi.d.ts

// package.json

{
	"name": "my-app",
	"scripts": {
		"generate": "sh scripts/openapi-generate.sh"
	}
	"devDependencies": {
		"dotenv-cli": "^7.3.0"
	}
}

Result:

from openapi-typescript.