CARGO-WATCH(1)

NAME
cargo-watch - watches over your Cargo project's source

SYNOPSIS

DESCRIPTION
Watches over your project's source for changes, and runs Cargo commands when they occur.

COMMANDS

cargo subcommand
    Cargo subcommand to run when watched files are modified, and at startup, unless --postpone is specified.

This is essentially the same as <command> but with cargo prepended, except that in addition, cargo-specific options are applied, such as --features.

command
    Command to run when watched files are modified, and at startup, unless --postpone is specified.

All commands passed are joined together with &&.

Cargo commands (-x) are always executed before shell commands (-s).

If a trailing command is given with -- <command>, it supersedes all other commands.

OPTIONS

-h, --help
    Display this message.

-V, --version
    Display version information.

--debug
    Show debug output.

--why
    Show paths that changed.

-q, --quiet
    Suppress output from cargo-watch itself.

-w, --watch watch...
    Watch specific file(s) or folder(s).

By default, your entire project is watched, except for the target/ and .git/ folders, and your .ignore and .gitignore files are used to filter paths.

-i, --ignore pattern...
    Ignore a glob/gitignore-style pattern.

On Windows, patterns given to -i have forward slashes (/) automatically converted to backward ones () to ease command portability.

--no-gitignore
    Don’t use .gitignore files.

--no-ignore
    Don’t use .ignore files.

--ignore-nothing
    Ignore nothing, not even target/ and .git/.

-c, --clear
    Clear the screen before each run.

-C, --workdir path
    Change the working directory to the path given.

The default is the crate root, as found by cargo locate-project.

--postpone
    Postpone first run until a file changes.

--poll
    Force use of polling for file changes.

-d, --delay delay
    File updates debounce delay in seconds (default: 0.5).

--no-restart
    Don’t restart command while it’s still running.

--watch-when-idle
    Ignore events emitted while the commands run. Will become default behaviour in 8.0.

--features features
    List of features passed to cargo invocations.

The features will be passed to every supported cargo subcommand. For example, with this command:

    $ cargo watch --features foo,bar -x clean -x build -x doc

Both build and doc will be run with the foo and bar features, but clean won't.

--use-shell use-shell
    Use a different shell. E.g. --use-shell=bash. On Windows, try --use-shell=powershell, which will become the default in 8.0.

EXAMPLES
Run cargo check on file save:

    $ cargo watch

Run tests only:

    $ cargo watch -x test

Run check then tests:

    $ cargo watch -x check -x test

Run run with arguments:

    $ cargo watch -x 'run -- --some-arg'

Run an arbitrary command:

    $ cargo watch -- echo Hello world

Run with features passed to cargo:

    $ cargo watch --features 'foo,bar'

DETAILS

  Ignore files
.gitignore files are used by default to ignore paths to watch and trigger runs. To stop honouring them, pass --no-gitignore.

.ignore files in the same syntax are also used by default. This file can be used to specify files that should be ignored by cargo watch but checked into git, without constantly adding --ignore abc options on the command-line. Do note that .ignore files may also be used by other programs, like ripgrep(1). To stop honouring these, pass --no-ignore.

Cargo watch also has an internal list of default ignores on top of those specified in files, like target/ and .git/ and various other common types (logs, editor swap files, lockfiles, etc).

To skip absolutely all ignores, use the --ignore-nothing flag.

  Ignore syntax
See the glob::Pattern docs0 https://doc.rust-lang.org/glob/glob/struct.Pattern.html for a more detailed specification of the glob matching syntax used for --ignore.

On Windows, patterns should be specified with Windows-style (\\) separators. Unix-style separators (/) would not match Windows paths, which could be confusing and give the appearance of commandline ignores not working. For convenience / in commandline ignores are automatically translated to \\ when running on Windows, but one should still try to write the correct patterns for the platform, as there may be more subtle differences.

BUGS
Please open an issue1 https://github.com/watchexec/cargo-watch/issues, or look through the existing ones.

If you want more verbose output, try running with the --debug flag. Note that this will also enable debug mode for watchexec. When filing an issue, make sure to include a log with --debug enabled so problems can be diagnosed, as well as your --version and OS.

If your issue is a watchexec (our main upstream) issue, open it there2 https://github.com/watchexec/watchexec/issues directly. If you're not sure, feel free to open it on the cargo-watch issue tracker, but if it is a watchexec issue, it will transferred over anyway.

  KNOWN BUGS
In 7.8.0, the --workdir option changes the directory before any other options are processed, so e.g. --watch paths may not work as expected. This has to be fixed upstream, see watchexec#188 https://github.com/watchexec/watchexec/issues/188#issuecomment-829138116.

TROUBLESHOOTING
Always start by checking your version with cargo watch --version and, if necessary, upgrading to the latest one by checking the website linked above.

  RLS is slow while using cargo watch, or vice versa, or it's waiting for the project lock a lot
Cargo builds (and checks, and clippy, and tests because the tests have to be built) take out a lock on the project so two cargo instances don't run at the same time.

However, Rust Analyzer is much better at this, so use that instead of RLS.

  File updates seems to never trigger
Try using --poll to force the polling fallback.

If that still doesn't work, and you're using an editor that does "safe saving", like IntelliJ / PyCharm, you may have to disable "safe saving" as that may prevent file notifications from being generated properly.

Also try using the --why option to see if the paths you expect are changing.

  It runs repeatedly without touching anything
That can happen when watching files that are modified by the command you're running.

If you're only running compiles or checks (i.e. any command that only affects the target/ folder) and you're using -w, you might be confusing the target-folder-ignorer. Check your options and paths.

You can also use the --watch-when-idle flag to ignore any event that happens while the command is running. This will become the default in 8.0.

  It runs repeatedly only touching ignored files
Make sure the files you ignored are the only ones being touched. Use the --why option to see exactly which files were modified and triggered the restart. Some programs and libraries create temporary files that may not match a simple ignore pattern.

As above, you can also use the --watch-when-idle flag to help.

  I don't have colour in my cargo output / for cargo test
This sometimes happens on some terminal configurations or for test harnesses. A quick workaround (instead of going down the rabbit hole of debugging your console settings) is to pass --color=always to the command. E.g.

    $ cargo watch -x 'check --color=always'

For test (and bench) commands, you'll need to pass the flag to the underlying program instead of cargo:

    $ cargo watch -x 'test -- --color=always'

AUTHOR
Written and maintained by Félix Saparelli.

https://passcod.name

Project homepage:

https://watchexec.github.io/#cargo-watch

Public domain.