File Watchers

File Watchers allow you to automatically run command-line tools like compilers, formatters, or linters when you change or save a file in the IDE.

File Watchers have two dedicated code inspections:

The File Watcher available inspection is run in every file where a predefined File Watcher is applicable. If the project has no relevant File Watcher configured, CLion suggests to add one.
The File Watcher problems inspection is invoked by a running File Watcher and highlights errors specific to it.

You can use one of the available templates or configure a File Watcher from scratch. A configured File Watcher can be saved in your project settings or in the IDE settings and used in different projects.

When you open a file where a predefined File Watcher is applicable, CLion displays a pane where suggests activating it.
Click Yes to activate the File Watcher with the default configuration.
If you click No, CLion considers the suggested File Watcher suppressed. You can still create and enable it manually as described in Creating a File Watcher below.

For more information about File Watchers for specific tools, see the corresponding pages:

Note that using some of these tools in CLion requires that you install plugins on the Settings | Plugins page as described in Installing plugins from JetBrains Marketplace.

Before you start

Install and enable the File Watchers plugin on the Settings | Plugins page, tab Marketplace, as described in Installing plugins from JetBrains Marketplace.

Creating a File Watcher

In the Settings dialog (Ctrl+Alt+S) , click File Watchers under Tools. The File Watchers page opens showing a list of File Watchers that are already configured in this project and in the IDE.
Click and choose the predefined template from which you want to create a File Watcher. The choice depends on the tool you are going to use. To use a tool that is not on the list, choose Custom. The New Watcher dialog opens.
In the Name field, type the name of the File Watcher. By default, CLion suggests the name of the selected predefined template.

Configuring the expected type and location of input files

Use the controls in the Files to watch area to define the range of files where you want to apply the File Watcher.

From the File type list, choose the expected type of input files. The File Watcher will consider only files of this type as subject for analyzing and processing. File types are recognised based on associations between file types and file extensions.
By default, the field shows the file type in accordance with the chosen predefined template.
Select the Scope in which the File Watcher is applicable.
Changes in these files will invoke the File Watcher either immediately or upon save or frame deactivation, depending on the status of the Auto-save edited files to trigger the watcher checkbox.
Select one of the predefined scopes from the list. For a project-level File Watcher, you can also click to configure a custom scope in the Scopes dialog that opens.
- All Places: all the scopes listed below.
- Project Files: all the files within the project roots.
- Scratches and Consoles: all the files from the Scratches and Consoles directory located in the Project tool window.
- Open Files: all the files that are currently opened in the editor.
- Current File: the file opened in the active editor tab.
Alternatively, click and configure a custom scope in the Scopes dialog that opens.
For more information, refer to Scopes and file colors.
Optionally: specify how you want the File Watcher to deal with dependencies. A root file is a file that is not included (for example via import) in any other file within the specified scope.
- To run the File Watcher only against root files, select the Track only root files checkbox.
- Clear the checkbox to run the File Watcher against the file from which it is invoked and against all the files in which this file is recursively included within the specified scope.
Note that the Scope setting overrides the Track only root files checkbox setting: if a dependency is outside the specified scope, the File Watcher is not applied to it.
This option is available only for Babel, Closure Compiler, Jade, Less, Sass/SCSS, Stylus, and UglifyJS.

Configuring interaction with the external tool

In the Tool to run on changes area, specify the tool to use, the arguments to pass to it, the expected output file types, and so on.

In the Program field, specify the path to the executable file of the tool (.exe, .cmd, .bat, or other depending on the specific tool).
- To use the program filename instead of its full path, add the path to its folder to the PATH environment variable.
- On Windows, you can skip the .com, .exe, .cmd or .bat extension.
- To use a jar archive, specify the absolute path to it. Alternatively, to use a relative path, add its parent folder to the CLion path variables on the Appearance & Behavior | Path Variables page of the IDE settings Ctrl+Alt+S.
In the Arguments field, define the arguments to pass to the tool.
Arguments are usually specified using macros, for example, $FileName$ or $FileNameWithoutExtension$ , that will be replaced with the actual filenames.
Type the macros manually or click and select the relevant pattern fom the list in the Macros dialog that opens.
When specifying the arguments, follow these rules:
- Use spaces as separators.
- If an argument contains spaces, enclose them or the entire argument in double quotes: some" "arg or "some arg".
- If an argument contains double quotes, use backslashes to escape them: -Dmy.prop=\"quoted_value"\.
In the Output paths to refresh field, specify the files where the tool stores its output: the resulting source code, source maps, and dependencies. Based on these settings, CLion recognizes the files generated through compilation.
Changing the value in the Output paths to refresh field does not make the tool store its output in another place. If you still need to do that, specify the desired custom output location in the Arguments field: type the output paths with colons as separators and use macros.
Output paths are usually specified using macros. Type the path manually or click and select the relevant pattern from the list.
Expand the
Working Directory and Environment Variables hidden area.
Define the environment variables. For example, specify the PATH variable for the tools that are required for starting the tool you are configuring but are not referenced in the path to it. In most cases, it is Node.js or ruby.exe. Such situation may result from custom manual installation instead of installation through the Node Package Manager (npm) or gem manager.
In the Working directory field, specify the directory to which the tool will be applied.
Because the tool is always invoked in the context of a file, the default working directory is the directory of the current file. The default working directory is specified in all predefined templates with the $FileDir$ macro. To specify a custom working directory, type the path to it in the field, or click and select the directory in the Select Path dialog, or click and select the desired macro from the list in the Macros dialog.
If you leave the Working Directory field empty, CLion uses the directory of the file where the File Watcher is invoked.

Configuring advanced options

In the Advanced Options area, customize the default behaviour of the File Watcher.

Specify the events that will invoke the File Watcher:
- To invoke the File Watcher as soon as any changes are made to the source code, select the Auto-save edited files to trigger the watcher checkbox.
  When the checkbox is cleared, the File Watcher starts upon save (File | Save All) or when you move the focus from CLion (on frame deactivation).
- By default, the File Watcher wakes up on any saved change, including the updates received from your version control system when you, for example, check out a branch. To ignore such changes and invoke the File Watcher only when you update your code in CLion, clear the Trigger the watcher on external changes checkbox.
Specify whether you want the File Watcher to interact with the CLion syntax parser:
- When the Trigger watcher regardless of syntax errors checkbox is selected, the File Watcher start regardless of the syntactical correctness of a file. The File Watcher will start upon update, save, or frame deactivation, depending on the status of the Auto-save edited files to trigger the watcher checkbox.
- When the Trigger watcher regardless of syntax errors checkbox is cleared, the File Watcher ignores all triggers in files that are syntactically invalid and starts only in error-free files.
Use the Create output file from stdout checkbox to specify how you want to generate the output file.
- When the checkbox is selected, CLion reads the native tool's output standard output stream (stdout) and generates the resulting files from it.
- When the checkbox is cleared, the tool writes its output directly to the files specified in the Output paths to refresh field.
In the Show console list, choose when you want the File Watcher to open the console.
- Always: with this option, the console always opens after the tool execution is completed.
- On error: with this option, the console opens after the tool execution only when the Exit code is different from 0.
- Never: choose this option to suppress opening the console at all.

Showing information reported by File Watcher in the editor

If the tool configured in the File Watcher reports errors or warnings about your code with the links to the files and specific lines, you can see this information right in the editor:

In Settings | Editor | Inspections, enable the inspection File Watcher Problems.
In the Output Filters field of the Edit Watcher dialog, describe the format of the output you want to match. Use the macros $FILE_PATH$ , $LINE$ , and $MESSAGE$ for that. You need to avoid using special symbols like braces and dot with \. The text matched with the $MESSAGE$ macro will be shown in the editor.

Saving, enabling, and disabling File Watchers

Once you’ve saved the new File Watcher, you can decide if it’s going to be available only in the current project (select Project from the Level list) or for all projects (select Global).

To enable or disable a File Watcher, open the Settings dialog (Ctrl+Alt+S) , go to Tools | File Watchers, and select or clear the checkbox next to it.
When a File Watcher is enabled, it starts automatically as soon as a file of the selected type and in the selected scope is changed or saved, refer to Configuring advanced options.
If an error occurs while a File Watcher is running, the File Watcher is automatically disabled. To restore the status, enable the File Watcher manually.

Enabling global File Watchers for new projects

Global File Watchers can be automatically enabled in all new projects that you create in the future.

Open the Settings for New Projects dialog (File | Settings for New Projects) , go to Tools | File Watchers, and select the checkboxes next to the required File Watchers.
Alternatively, on the Welcome Screen, select Settings from the Configure list. In the dialog that opens, select the checkboxes next to the relevant File Watchers.

Troubleshooting File Watchers

There might be a red error message next to the File Watcher in the list in Settings | Tools | File Watchers.

Here is a list of possible errors:

Reported Problem	Problem Description	Workaround
`Unknown Scope error`	The File Watcher uses a scope that is not defined in this project.	Double-click the watcher and select an available scope or create a new one.
`Not found error`	The project uses a global File Watcher that was removed.	Delete the watcher from the list using the Remove button or edit it to create a new global watcher with the same name.
CLion runs numerous identical File Watcher tasks	After a bulk update, for example, from your VCS, CLion runs a separate File Watcher task for each saved file.	Add a file-specific macro (like `&FileNameWithoutExtension&`) in the Arguments field, refer to Configuring interaction with the external tool.

Last modified: 11 February 2024