When you want to fire an event no matter how a process exits:

• reaching the end of execution.
• explicitly having process.exit(code) called.
• having process.kill(pid, sig) called.
• receiving a fatal signal from outside the process

Use signal-exit.

var onExit = require('signal-exit')

onExit(function (code, signal) {
  console.log('process exited!')
})

var remove = onExit(function (code, signal) {}, options)

The return value of the function is a function that will remove the handler.

Note that the function only fires for signals if the signal would cause the proces to exit. That is, there are no other listeners, and it is a fatal signal.

• alwaysLast: Run this handler after any other signal or exit handlers. This causes process.emit to be monkeypatched.