From 503845b758ad51085319c491cf2c9367542ef1f9 Mon Sep 17 00:00:00 2001
From: Ritvik Saraf <13ritvik@gmail.com>
Date: Fri, 20 Apr 2018 05:11:06 +0530
Subject: [PATCH] updated readme with custom event listeners

---
 Readme.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Readme.md b/Readme.md
index a29da4013..49b935881 100644
--- a/Readme.md
+++ b/Readme.md
@@ -356,6 +356,22 @@ function make_red(txt) {
   Output help information and exit immediately.
   Optional callback cb allows post-processing of help text before it is displayed.
 
+
+## Custom event listeners
+ You can execute custom actions by listening to command and option events.
+
+```js
+program.on('option:verbose', function () {
+  process.env.VERBOSE = this.verbose;
+});
+
+// error on unknown commands
+program.on('command:*', function () {
+  console.error('Invalid command: %s\nSee --help for a list of available commands.', program.args.join(' '));
+  process.exit(1);
+});
+```
+
 ## Examples
 
 ```js