TL;DR Sometimes you need to attach the IntelliJ IDEA debugger to a running JVM process. Using the Attach to process... action frequently, however, can slow you down a little bit. You might want the IntelliJ IDEA debugger to attach automatically to any process that was spawned outside of IntelliJ IDEA (from the terminal, a build tool, etc.) without having to interact with IntelliJ IDEA each time.

IntelliJ IDEA is an IDE - an Integrated Development Environment. I want to focus on the "Integrated" in this post, which is based on my Scala Days talk. Many developers believe in the "one tool, one job" UNIX philosophy of tooling: A small set of orthogonal, powerful command line tools that individually only do one job, but do it well, and connect through a common interface: stdin/stdout stream