websocketd

websocketd turns any program that reads stdin and writes stdout into a WebSocket server.

websocketd --port=8080 --sameorigin ./count.sh

count.sh is an ordinary script. It reads lines from stdin, writes lines to stdout, and has no idea a WebSocket exists.

Each browser that connects gets its own copy of the script running. What the browser sends arrives on the script's stdin. Every line the script prints goes back to that browser as a WebSocket message. That is the whole integration: no library to import, no framework, no change to the program.

websocketd starts one process per connection. Connections are fully isolated from each other and share nothing, so there is no built-in broadcast. See the process model for what that buys and what it rules out.

Next: install the binary , or read the CLI flag reference if you already have it.