NodeJS - How do I detect other copies of my program? - node.js

Question

I have written a NodeJS command-line program with two modes:
mode foo: runs forever until the user presses Ctrl+C
mode bar: runs once
If the user is already running the program in mode foo, then running it again in mode bar will cause errors. Thus, when the user invokes mode bar, I want to search for all other existing copies of my command-line program that are running and kill them (as a mechanism to prevent the errors before they happen).
Getting a list of processes in NodeJS is easy, but that doesn't help me much. If I simply kill all other node processes, then I might be killing other programs that are not mine. So, I need to know which specific node processes are the ones running my app. Is it even possible to interrogate a process to determine that information?
Another option is to have my program write a temporary file to disk, or write a value to the Windows registry, or something along those lines. And then, before my program exists, I could clean up the temporary value. However, this feels like a precarious solution, because if my program crashes, then the flag will never be unset and will remain orphaned forever.
What is the correct solution to this problem? How can I kill my own application?

Answer 1

I was able to solve this problem using PowerShell:
import { execSync } from "child_process";
const CWD = process.cwd();
function validateOtherCopiesNotRunning(verbose: boolean) {
if (process.platform !== "win32") {
return;
}
// From: https://securityboulevard.com/2020/01/get-process-list-with-command-line-arguments/
const stdout = execPowershell(
"Get-WmiObject Win32_Process -Filter \"name = 'node.exe'\" | Select-Object -ExpandProperty CommandLine",
verbose,
);
const lines = stdout.split("\r\n");
const otherCopiesOfMyProgram= lines.filter(
(line) =>
line.includes("node.exe") &&
line.includes("myProgram") &&
// Exclude the current invocation that is doing a 1-time publish
!line.includes("myProgram publish"),
);
if (otherCopiesOfMyProgram.length > 0) {
throw new Error("You must close other copies of this program before publishing.");
}
}
function execPowershell(
command: string,
verbose = false,
cwd = CWD,
): string {
if (verbose) {
console.log(`Executing PowerShell command: ${command}`);
}
let stdout: string;
try {
const buffer = execSync(command, {
shell: "powershell.exe",
cwd,
});
stdout = buffer.toString().trim();
} catch (err) {
throw new Error(`Failed to run PowerShell command "${command}":`, err);
}
if (verbose) {
console.log(`Executed PowerShell command: ${command}`);
}
return stdout;
}