Ok the title is a bit long but why google create such a nice debug interface and make it so difficult to access it.

1. open chrome with remote debug enabled

chromium --remote-debugging-port=9222 https://github.com/

2. Install websocat to create websocket to chrome

sudo pacman -S websocat

3. Find magic chrome ws url. To do that visit following url

http://127.0.0.1:9222/json/list

4. Connect to the websocket

websocat ws://127.0.0.1:9222/devtools/browser/<GUID>

5. Execute magic command. Here just scrolling the page

{"id": 1, "method": "Runtime.evaluate", "params": {"expression": "document.documentElement.scrollTop = 600"}}

---

Few Notes

• Websocket URL directly from chrome(stdout) don’t address any target page. Stick to http://127.0.0.1:9222/json/list or see cdp tutorial for further information.
• For automated command execution in debug session you can use following scripting

  chrome_loop.sh
  inotifywait -q -m -e close_write cmd | 
  while read -r filename event; do 
       cat cmd | websocat -n1 ws://127.0.0.1:9222/devtools/page/<GUID>
  done

  cmd
  {"id": 1, "method": "Runtime.evaluate" , "params": {"expression": "alert('hi')"}}