Software development often involves running the same commands over and over. Boring!

watchexec is a simple, standalone tool that watches a path and runs a command whenever it detects modifications.

Example use cases:

• Automatically run unit tests
• Run linters/syntax checkers
• Rebuild artifacts

• Simple invocation and use, does not require a cryptic command line involving xargs
• Runs on OS X, Linux, and Windows
• Monitors current directory and all subdirectories for changes
• Coalesces multiple filesystem events into one, for editors that use swap/backup files during saving
• Loads .gitignore and .ignore files
• Uses process groups to keep hold of forking programs
• Provides the paths that changed in environment variables or STDIN
• Does not require a language runtime, not tied to any particular language or ecosystem
• And more!

Watch all JavaScript, CSS and HTML files in the current directory and all subdirectories for changes, running npm run build when a change is detected:

$ watchexec -e js,css,html npm run build

Call/restart python server.py when any Python file in the current directory (and all subdirectories) changes:

$ watchexec -r -e py -- python server.py

More usage examples: in the CLI README!

• With your package manager for Arch, Debian, Homebrew, Nix, Scoop, Chocolatey…
• From binary with Binstall: cargo binstall watchexec-cli
• As pre-built binary package from Github
• From source with Cargo: cargo install --locked watchexec-cli

All options in detail: in the CLI README, in the online help (watchexec -h, watchexec --help, or watchexec --manual), and in the manual page.

Watchexec pairs well with:

• checkexec: to run only when source files are newer than a target file
• just: a modern alternative to make
• systemfd: socket-passing in development

• watchexec library: to create more specialised watchexec-powered tools.
  • watchexec-events: event types for watchexec.
  • watchexec-signals: signal types for watchexec.
  • watchexec-supervisor: process lifecycle manager (the exec part of watchexec).
• clearscreen: to clear the (terminal) screen on every platform.
• process wrap: to run commands in process groups.
• ignore files: to find, parse, and interpret ignore files.
• project origins: to find the origin(s) directory of a project.
• notify: to respond to file modifications (third-party).

Selected downstreams of watchexec and associated crates:

• cargo watch: a specialised watcher for Rust/Cargo projects.
• cargo lambda: a dev tool for Rust-powered AWS Lambda functions.
• create-rust-app: a template for Rust+React web apps.
• devenv.sh: a developer environment with nix-based declarative configs.
• dotter: a dotfile manager.
• ghciwatch: a specialised watcher for Haskell projects.
• tectonic: a TeX/LaTeX typesetting system.