Install watcher with Homebrew, apt, Nix

Project links

• Homepage
• Upstream docs
• Package manager page

Commands and aliases

• wtr.watcher

Project history

Watcher appeared publicly as a Show HN post on October 18, 2022, where the author described it as a simple, efficient, dependency-free, header-only filesystem event watcher. In that launch discussion, the author explained the early implementation tradeoff: a baseline standard-library watcher, OS-specific support where useful, and attention to correctness on large trees rather than simply wrapping one kernel notification API.

The repository's release history shows the project maturing from the 0.9 and 0.10 series into 0.12, 0.13, and 0.14. By the 0.14.0 release, the project had added a Go package, refined Windows DLL exports for the C interface, and improved CMake behavior for subproject use. The 0.13.7 and later releases also show the kind of maintenance expected from filesystem tools: inotify rename fixes, Darwin/FSEvents fixes, pkg-config files, version flags, C++17 portability, and test/CI updates.

Adoption history

Watcher remains a modest project compared with older file watching services, but its adoption signals are visible in developer packaging channels. The GitHub project page shows hundreds of stars, the README badges point to Conan, Cargo, PyPI, Go modules, Homebrew, Nix, and GNU Guix, and release artifacts are published for multiple operating systems and architectures.

How it is used

The README presents Watcher as both a library and a program. Library users call a `watch` function or class with a path and callback, then receive event objects containing path name, path type, effect type, event time, and an associated path for rename-style events. CLI users can run the bundled watcher program and pipe the resulting JSON stream into other tools.

The project is unusually binding-heavy for its size. The README includes quick starts for C++, C, Python, Rust, Node.js, and Go, which positions Watcher less as an end-user automation command like watchexec and more as a portable event substrate for developers who want file-change events inside their own applications.

Why package nerds care

Watcher is significant to package nerds because it tackles a famously awkward portability problem: every major OS exposes different filesystem event semantics, and correctness around renames, recursive trees, symlinks, and editor save patterns is full of edge cases. A small, dependency-minimal C++17 implementation with pkg-config, CMake, C ABI, and language bindings is exactly the sort of library packagers scrutinize for ABI surface, portability, testability, and platform-specific behavior.

Timeline

• 2022-10-18: Watcher is introduced on Hacker News as a filesystem watcher.
• 2023-2024: 0.10 through 0.12 release tags mark early public library and CLI maturation.
• 2025-09-01: 0.13.7 adds pkg-config files, a CLI version flag, C++17 portability fixes, and inotify rename fixes.
• 2025-12-08: 0.14.0 adds a Go package and improves C/CMake integration.
• 2026-02-23: 0.14.5 fixes cross-directory path-name caching and inotify/Linux reporting.

Related projects

• Watcher sits near fsnotify-style libraries, kqueue/inotify/FSEvents/ReadDirectoryChangesW wrappers, Watchman, watchexec, entr, and language-specific file-watching packages. Its closest distinction is being an embeddable C++ library with a CLI, rather than a long-running service or a command rerunner.

Sources

• https://conan.io/center/recipes/watcher
• https://github.com/e-dant/watcher
• https://github.com/e-dant/watcher/releases
• https://news.ycombinator.com/item?id=33247155