Watchexec

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

Features

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!

Quick start

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!

Install

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.

Augment

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

Extend

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.
command group: 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).

Downstreams

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.