To stream command output as it is being executed, pass the onStdout, onStderr callbacks to the commands.run() method in JavaScript or the on_stdout, on_stderr callbacks to the commands.run() method in Python. 
import { Sandbox } from 'novita-sandbox/code-interpreter'

const sandbox = await Sandbox.create()
const result = await sandbox.commands.run('echo hello; sleep 1; echo world', {
  onStdout: (data) => {
    console.log(data)
  },
  onStderr: (data) => {
    console.log(data)
  },
})

console.log(result)

await sandbox.kill()