A watch utility written in Go

go get


wu (呜~)

A minimal Watch Utility who can run and restart specified command in response to file changes automatically.

This utility is intended to provide a tiny tool to automate the Edit-Build-Run loop of development. Although it is quite similar to watch tasks of Grunt or Gulp, wu is designed to be just a single command with simplest interfaces to work with.


To install wu from source code, you have to install Golang's tool chain first. Then run:

go get
go install

Precompiled version can be found here.


Run wu -h for help message:

Usage: wu [options] [command]
  -config string
        Config file (default ".wu.json")
  -dir string
        Directory to watch
  -pattern string
        Patterns to filter filenames
        Save options to conf


You just run you command with wu, wu will run your command at the start, try to terminate previous when new changes take place and then start running a new one. You can stop the process by sending a SIGINT signal (typically by CTRL-C):

wu sleep 10


Start watching...
- Running command: sleep 10
- Terminated.
File changed: /path/to/changed/file.txt
- Running command: sleep 10
- Done.
File changed: /path/to/changed/file.txt
- Running command: sleep 10
- Done.
Shutting down...

Usually you can only run one command with wu, but it doesn't prevent you from running complex command with sh, bash or other shell command:

wu sh -c 'echo "START" && sleep 5 && echo "END"'


Start watching...
- Running command: sh -c echo "START" && sleep 5 && echo "END"
- Done.

You can specified a pattern to filter the files to watch. Multiple patterns should be seperated by spaces or commas:

wu -pattern="*.js, *.html"

Output (If no command specified, wu just log changed files):

Start watching...
File changed: /path/to/changed/file.js
File changed: /path/to/changed/file.html

One practical use case is to use wu with some light weight web frameworks, For example, you can start a server written in go by:

wu -pattern="*.go" go run main.go

wu will try to read config file under current directory at the start (default: .wu.json), you can user -config flag to specify the config file by hand. Use -save flag to save current options.

wu -pattern="*.go" -save go build
# A `.wu.json` has been created

wu # Running `wu` without any options, it will read from `.wu.json`