>> Basically allows you to run a command triggered by file changes, without polling the file system.
http://lpan.io/one-liner-dropbox-client/
Very interesting.
So this is what intelli j complains about.
For an intelligent IDE it is essential to be in the know about any external changes in files it working with - e.g. changes made by VCS, or build tools, or code generators etc. For that reason, IntelliJ platform spins background process to monitor such changes.
Inotify requires a "watch handle" to be set for each directory in the project. Unfortunately, the default limit of watch handles may not be enough for reasonably sized projects, and reaching the limit will force IntelliJ platform to fall back to recursive scans of directory trees.
The inotify API provides a mechanism for monitoring filesystem events. Inotify can be used to monitor individual files, or to monitor directo- ries. When a directory is monitored, inotify will return events for the directory itself, and for files inside the directory.
http://man.he.net/?section=all&topic=inotify