# $ cargo watch
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Cargo Watch watches over your project's source for changes, and runs Cargo
commands when they occur.
If you've used [nodemon], [gulp], [guard], [watchman], or similar others,
it will probably feel familiar.
$ cargo install cargo-watch
$ cargo install --force cargo-watch
Or clone and build with `$ cargo build` then place in your $PATH.
By default, it runs `check` (which is available [since Rust 1.16][st-check]).
You can easily override this, though:
$ cargo watch [command...]
A few examples:
$ cargo watch test
$ cargo watch run
$ cargo watch doc
$ cargo watch test bench
$ cargo watch "build --release"
$ cargo watch "build --release" "test test_"
### Force polling
If the commands are never triggering, or you're getting this error:
ERROR:cargo_watch: Failed to init notify
You can try the alternative (polling) file watcher, by passing `--poll`.
### Clear screen
If you prefer to clear the screen before running commands, you can pass the
`--clear` flag. If you want to clear the screen in-between individual commands,
you can use `clear` as a command, e.g.
$ cargo watch check clear test
### Cargo run
~~Cargo Watch has special behaviour with `run` commands: it will restart the
process on file change. This works especially well when developing servers
or other applications that never return on normal operation.~~
⚠ This currently doesn't work properly, see [#25](https://github.com/passcod/cargo-watch/issues/25). ⚠
As a result of this long-standing issue (a contributed fix would be immensely
appreciated, but I'll get to it eventually), if you're developing servers it's
probably better to use an alternative, like [nodemon] if you have Node, or
[watchexec] if you like Rust tooling.
## Details and tips
It pairs well with [dybuk], the compiler output prettifier:
$ cargo watch |& dybuk
Just like any Cargo command, it will run from any project subdirectory.
Cargo Watch will ignore everything that's not a Rust file, and files that start
with either a dot (`.foo.rs`) or a tilde (`~foo.rs`).
It uses the [notify] crate for file events, so it supports all platforms, some
more efficiently than others (if you use the big three — Linux, Mac, Windows —
you will be fine).
If your Cargo Watch fails to watch some deep directories but not others, and you
are on Linux, you may have hit [the inotify watch limit](http://blog.sorah.jp/2012/01/24/inotify-limitation).
You can either increase the limit (instructions are on the previous link and at
[this Guard wiki page](https://github.com/guard/listen/wiki/Increasing-the-amount-of-inotify-watchers)),
or you can stop whatever it is that's consuming so many inotify watches.
It [does not yet][i-52] support Cargo workspaces.
Created by [Félix Saparelli][passcod] and [awesome contributors][contributors].