Rerun is a command-line utility that automatically restarts a program when relevant files in a watched directory change. It wraps the Listen gem to efficiently monitor the filesystem and supports graceful process termination via configurable signal sequences (default TERM, INT, KILL). The tool provides real-time keypress commands (restart, force restart, clear, pause, quit) and optional desktop notifications via growlnotify, terminal-notifier, or notify-send. The codebase is a single Ruby gem with a CLI entry point (bin/rerun) and a clear separation of concerns: Runner for process management, Watcher for filesystem listening, Options for CLI parsing, and Notification for cross-platform alerts. It was last actively developed around 2014-2018, with a documented version 0.14.0 in 2023, but open issues and pull requests from 2014 suggest it is no longer maintained.