Deno subprossess live monitoring.

README.md

This is to demonstrate that you can monitor programs that are currently running (as opposed to only once the program has exited.

Generator generates a specified number of Alpha and Beta line sets.

Monitor passes specified number of lines in and looks for Al (Alpha) and when it finds it, it logs to console.

generator.ts

import { delay } from "https://deno.land/std@0.82.0/async/delay.ts";
import { parse } from "https://deno.land/std@0.82.0/flags/mod.ts";
const parsed = parse(Deno.args);

for(let x = 0; x < parsed._[0]; x++){
    console.log("Alpha");
    await delay(250);
    console.log("Beta");
    await delay(250);
}

monitor.ts

import { TextProtoReader } from "https://deno.land/std@0.82.0/textproto/mod.ts";
import { BufReader } from "https://deno.land/std@0.82.0/io/bufio.ts";
import { parse } from "https://deno.land/std@0.82.0/flags/mod.ts";
const parsed = parse(Deno.args);

const p = Deno.run({
  cmd: [
    "deno",
    "run",
    "https://gist.githubusercontent.com/jcc10/8e22746293b594fe4fb43ef4f4f5ff88/raw/d01e5d75b5ea6baf60a0681259e72967cbe84b32/generator.ts",
    `${parsed._[0]}`
  ],
  stdout: "piped",
  stderr: "piped",
});

const reader = new TextProtoReader(BufReader.create(p.stdout));

let count = 0;

console.log("Started");

while(true){
    const line = await reader.readLine();
    if(line === null) break;
    if(line?.includes("Al")){
      count++;
      console.log(`Got ${count}...`)
    }
}

console.log("Ended")