fswatch

Watch directory for changes

$ fswatch [/path/to/directory]

$ fswatch -o [/path/to/directory] | xargs -n1 -I{} [command]

$ fswatch -r [/path/to/directory]

$ fswatch --include ".*\\.txt$" --exclude ".*" [/path/to/directory]

$ fswatch -1 [/path/to/directory]

$ fswatch [/path/dir1] [/path/dir2]

$ fswatch -t [/path/to/directory]

$ fswatch -l [2] [/path/to/directory]

fswatch [options] paths...

fswatch is a cross-platform file change monitor that detects filesystem changes and outputs affected paths. It uses native platform APIs (inotify on Linux, FSEvents on macOS, kqueue on BSD) for efficient monitoring.
The tool outputs changed file paths to stdout, which can be piped to other commands for automated workflows like rebuilding projects, running tests, or reloading services. It supports recursive monitoring and filtering by file patterns.
fswatch is useful for development workflows, build automation, backup triggers, and any scenario where actions should be triggered by file modifications.

-o, --one-per-batch

Print single event per batch (for counting).

Recurse into subdirectories.

Print timestamps with events.

Set latency (debounce period).

Exit after first event.

Separate paths with NUL character.

Filter by event type.

Include only matching files.

Exclude matching files.

Use specific monitor backend.

Verbose output.

Print numeric event codes.

System limits on inotify watches may affect large directory monitoring (adjustable via /proc/sys/fs/inotify/maxuserwatches). Different backends have different capabilities. Latency affects responsiveness vs. batching trade-off.

fswatch was created by Enrico M. Crisostomo in 2014 to provide a unified, cross-platform file monitoring solution. It was designed to replace platform-specific tools with a single utility that uses native APIs. The project continues to be maintained and supports Linux, macOS, Windows, and BSD systems.

inotifywait(1), entr(1), watchexec(1), watchman(1)