Build Awesome Command-Line Applications in Ruby 2

Trapping Signals Sent from Other Apps

Our two example apps, db_backup.rb and todo, are not long-running apps. They start up very quickly and exit when they’re done. While this is very common for command-line apps, there are occasions where we will need to write a long-running process. You may have a process that runs all the time, polling a message queue for work to do, or you may need to run a process that monitors other processes. Or, you might have a task that just takes a long time. In each case, you’ll want a way for a user to send information to your running app.

The most common example is to stop an app from running. We do this all the time by hitting Ctrl-C when an app is running in our terminal. This actually sends the app a signal ...