FILENOTIFYCHANGE

FILENOTIFYCHANGE is a term used in file system monitoring to denote an event type that signals a change has occurred to a file or directory being watched. It serves as a generalized indicator within notification APIs, callbacks, or event streams that clients should process an update related to a specific path.

In practice, a FILENOTIFYCHANGE event is accompanied by metadata describing the change. Typical fields include the affected path, a timestamp, and the kind of change (for example, created, modified, deleted, or renamed). Some implementations also provide additional details such as the previous and new paths for renamed items, file size, or attribute changes.

Usage patterns for FILENOTIFYCHANGE vary. It can be emitted as part of an event stream that developers consume in real time, or as entries in a queue during a polling cycle. In cross-platform libraries, FILENOTIFYCHANGE often serves as a unifying abstraction over platform-specific file watching mechanisms, allowing applications to respond to changes without handling low-level API differences.

Relation to platform specifics exists. In Windows, similar concepts appear as actions reported by the ReadDirectoryChangesW API, while in other ecosystems, equivalent events may be exposed through dedicated file system watcher APIs. FILENOTIFYCHANGE may function as the library’s internal representation of these platform events, mapped to a consistent event shape for application code.

Considerations when using FILENOTIFYCHANGE include debouncing to avoid duplicate notifications, recursive watching of directories, handling symbolic links, permission constraints, and ensuring robust race-condition handling in response to rapid or concurrent changes. See also: file system events, directory watching, and notify filters.