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Understanding Window Classes and Classnames with xdotool

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When working with Linux, understanding the properties of windows can be a vital part of system administration and scripting tasks. One such tool that can be particularly useful is xdotool, a command-line utility that allows you to programmatically control X11 windows. In this article, we will delve into the concept of window classes and classnames and how to manipulate them using xdotool.

Quick Answer

Window classes and classnames are properties of X11 windows that can be used to identify and interact with them. They help categorize and distinguish between different windows. Using the xdotool command-line utility, you can search for windows based on their class or classname, allowing you to target specific windows for manipulation.

What are Window Classes and Classnames?

In the context of X11 windows, the terms “class” and “classname” refer to properties of a window that can be used to identify and interact with it.

Class refers to the general category or type of applications to which a window belongs. It’s a broad identifier that groups similar applications together. For instance, all Google Chrome windows would typically fall under the “google-chrome” class.

Classname, on the other hand, refers to a specific instance of an application. It’s a more granular identifier, often used to distinguish between different windows of the same application. For example, each individual Google Chrome window would have its unique classname.

How to Find Class and Classname of a Window

To find out the class and classname of a window, you can use the xprop command. This command is used to display window and font properties in an X server.

Open a terminal and run the following command:

xprop | grep 'CLASS'

After running this command, your cursor will change into a crosshair. Click on the window you want to inspect. The terminal will then display the class and classname of the selected window. The output will be in the format:

WM_CLASS(STRING) = "classname", "class"

Using xdotool to Search for Windows

With xdotool, you can search for windows based on their class or classname. This can be particularly useful when scripting, as it allows you to target specific windows for manipulation.

Here’s an example of how to search for a window with the class “google-chrome”:

xdotool search --class google-chrome

In this command, search is the function we’re calling, --class is the option that tells xdotool we’re searching based on class, and google-chrome is the class we’re looking for.

This command will return the window ID of the first window it finds that matches the class “google-chrome”. You can then use this window ID with other xdotool commands to manipulate the window.


Understanding window classes and classnames is a crucial part of effectively using xdotool and other X11 window manipulation tools. By using the xprop command, you can easily find out the class and classname of any window. With xdotool’s search function, you can then find and manipulate windows based on their class or classname. With these tools at your disposal, you’ll be well-equipped to handle any window-related tasks in your Linux environment.

How can I use xdotool to manipulate windows?

To manipulate windows using xdotool, you can use commands such as windowactivate, windowmove, windowresize, and windowkill. These commands allow you to activate, move, resize, and close windows respectively. You can specify the window to manipulate using its window ID, class, or classname.

Can I use xdotool to automate repetitive tasks?

Yes, xdotool is commonly used for automating repetitive tasks. By combining xdotool commands with scripts or shell commands, you can create automation scripts to perform tasks such as opening applications, interacting with windows, and simulating keyboard and mouse input.

How can I simulate keyboard input with xdotool?

To simulate keyboard input with xdotool, you can use the type command. For example, to type the string "Hello, World!" in the currently focused window, you can use the following command: xdotool type "Hello, World!". You can also use the key command to simulate pressing specific keys or key combinations.

Can I use xdotool to automate web browsers?

Yes, xdotool can be used to automate web browsers. By combining xdotool with other tools like xdg-open or xdotool type, you can open URLs in a browser, interact with browser windows, and simulate keyboard input to fill out forms or navigate webpages.

How can I install xdotool on my Linux system?

To install xdotool on most Linux distributions, you can use your package manager. For example, on Ubuntu or Debian-based systems, you can run sudo apt-get install xdotool. On Fedora or CentOS systems, you can use sudo dnf install xdotool or sudo yum install xdotool respectively.

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