#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

##Features

• Simple invocation and use
• Runs on OS X, Linux and Windows
• Monitors current directory and all subdirectories for changes (use --watch to override)
  • Uses most efficient event polling mechanism for your platform (except for BSD)
• Coalesces multiple filesystem events into one, for editors that use swap/backup files during saving
• By default, uses .gitignore to determine which files to ignore notifications for
• Support for watching files with a specific extension
• Support for filtering/ignoring events based on glob patterns
• Launches child processes in a new process group
• Sets the following environment variables in the child process:
  • $WATCHEXEC_UPDATED_PATH the path of the first file that triggered a change
  • $WATCHEXEC_COMMON_PATH the longest common path of all of the files that triggered a change
• Optionally clears screen between executions
• Optionally restarts the command with every modification (good for servers)
• Does not require a language runtime

##Anti-Features

• Not tied to any particular language or ecosystem
• Does not require a cryptic command line involving xargs

##Usage Examples

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

$ watchexec --exts js,css,html make

Watch all files below src and subdirectories for changes, running make test when a change is detected:

$ watchexec --watch src make test

Call make test when any file changes in this directory/subdirectory, except for everything below target:

$ watchexec -i target make test

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

$ watchexec -e py -r python server.py

Run make when any file changes, using the .gitignore file in the current directory to filter:

$ watchexec make

##Installation

###Cargo (nightly Rust only)

If you're running nightly Rust, install it using cargo:

$ cargo install watchexec

If you're using rustup, install it like this:

$ rustup toolchain install nightly
$ rustup run nightly cargo install watchexec

###OS X with Homebrew

$ brew install https://raw.githubusercontent.com/mattgreen/watchexec/master/pkg/brew/watchexec.rb

###Linux

For now, use the GitHub Releases tab to obtain the binary. PRs for packaging in various distros are welcomed.

###Windows

Use the GitHub Releases tab to obtain the binary. In the future, I'll look at adding it to Chocolatey.

##Building

Currently, watchexec requires a recent nightly Rust to build, due to use of unstable features.

##Credits

• notify for doing most of the heavy-lifting
• globset for super-fast glob matching