entr is a file-watching utility that runs arbitrary commands when files change.
The tool solves the problem of manually re-running commands during development by monitoring the filesystem and automatically triggering actions when watched files are modified. It works by leveraging platform-specific file monitoring mechanisms—inotify on Linux and kqueue on BSD and macOS—to detect changes and execute user-specified commands in response. This approach eliminates the need for manual intervention during iterative development workflows.
The tool suits developers who want to automate repetitive command execution during coding, testing, or building. It works well for test automation, where tests can run automatically whenever source files change, and for build workflows where recompilation or asset processing should trigger on file modifications. The project is particularly valuable for developers working in Unix-like environments who prefer a lightweight, command-line-based solution that integrates with existing shell scripts and build systems.
The project shows consistent maintenance with regular updates addressing bug fixes and platform compatibility. Development activity demonstrates responsiveness to user-reported issues and incremental improvements to core functionality. The codebase maintains focus on its core responsibility of file monitoring and command execution without scope creep into unrelated features.
