wat

wat is a tiny cross-platform, language-agnostic CLI for watching file changes and executing commands.

This tool is for my own personal use and may have breaking changes each minor version. If you use it, let me know how it goes!

The config file is a TOML file named watfile or watfile.toml. Example:

default = ["backend", "frontend"]

[init]
run = ["npm install --prefix frontend", "cargo fetch --manifest-path backend/Cargo.toml"]

[backend]
watch = ["backend/src/**", "backend/Cargo.toml"]
run = ["cd backend && cargo build"]

[frontend]
watch = ["frontend/src/**", "frontend/package.json", "frontend/package-lock.json"]
run = ["npm run build --prefix frontend"]

[serve-frontend]
watch = ["frontend/src/**", "frontend/package.json", "frontend/package-lock.json"]
interrupt = true
run = ["npm run dev --prefix frontend"]

[serve-backend]
watch = ["backend/src/**", "backend/Cargo.toml"]
interrupt = true
run = ["cd backend && cargo run"]

Top-level options:

• default: targets used when no target names are passed. Just run wat
• ignore: paths to skip

Each target supports:

• watch: paths or globs to watch. If this is not provided, or --once is used, the target only runs once.
• run: commands to execute on startup and on changes
• interrupt: kill the child process immediately when changes arrive. You'd want this for long-running processes, and I'm considering making this the default behavior.

run supports multiple commands. They are chained in the shell with &&, so run = ["cargo fmt --check", "cargo build", "cargo test"] behaves like cargo fmt --check && cargo build && cargo test

If you want two long-running processes, use two targets and run them together instead of putting both in one run list.

When chaining commands across sibling directories, prefer commands that do not depend on the previous working directory, such as npm --prefix ... or cargo --manifest-path .... Or if you need to use cd, handle it explicitly. Though this isn't very clean and I'm thinking about how to handle cases like this better.

install

Linux

curl -fsSL https://raw.githubusercontent.com/GageHowe/wat/main/scripts/install.sh | sh

MacOS

curl -fsSL https://raw.githubusercontent.com/GageHowe/wat/main/scripts/install-macos.sh | sh

Windows

irm https://raw.githubusercontent.com/GageHowe/wat/main/scripts/install.ps1 | iex

wat update automatically grabs these links and updates itself, and wat -v shows the current version