Handle OS Signals

This program makes use of an unstable Deno feature. Learn more about unstable features.

Concepts

  • Use the --unstable flag to access new or unstable features in Deno.
  • Deno.signal can be used to capture and monitor OS signals.
  • Use the dispose() function of the Deno.signal SignalStream to stop watching the signal.

Async iterator example

You can use Deno.signal() function for handling OS signals:

`

  1. /** * async-iterator-signal.ts */console.log("Press Ctrl-C to trigger a SIGINT signal");for await (const _ of Deno.signal(Deno.Signal.SIGINT)) {  console.log("interrupted!");  Deno.exit();}

`

Run with:

`

  1. deno run --unstable async-iterator-signal.ts

`

Promise based example

Deno.signal() also works as a promise:

`

  1. /** * promise-signal.ts */console.log("Press Ctrl-C to trigger a SIGINT signal");await Deno.signal(Deno.Signal.SIGINT);console.log("interrupted!");Deno.exit();

`

Run with:

`

  1. deno run --unstable promise-signal.ts

`

Stop watching signals

If you want to stop watching the signal, you can use dispose() method of the signal object:

`

  1. /** * dispose-signal.ts */const sig = Deno.signal(Deno.Signal.SIGINT);setTimeout(() => {  sig.dispose();  console.log("No longer watching SIGINT signal");}, 5000);
  2. console.log("Watching SIGINT signals");for await (const _ of sig) {  console.log("interrupted");}

`

Run with:

`

  1. deno run --unstable dispose-signal.ts

`

The above for-await loop exits after 5 seconds when sig.dispose() is called.