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How To Kill Unresponsive GUI Apps in Unity

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In the world of computing, it’s inevitable to encounter unresponsive applications. These can be frustrating, particularly when you’re working on something important. If you’re a Unity user, there are several ways to kill unresponsive Graphical User Interface (GUI) applications. This article will guide you through different methods, from using the xkill command, creating a keyboard shortcut, using the System Monitor, to scripting.

Quick Answer

To kill unresponsive GUI apps in Unity, you can use the xkill command by pressing Alt+F2, typing xkill, and clicking on the non-responsive window. Alternatively, you can create a keyboard shortcut for xkill by going to the Keyboard settings and assigning a key combination. The System Monitor can also be used to select and end unresponsive processes. Additionally, you can add a "Force Quit" option to the Unity launcher or use a script to send a SIGTERM signal to the currently active window.

Using the xkill Command

The xkill command is a simple and quick way to kill unresponsive applications. Here’s how to use it:

  1. Press Alt+F2 to open the Run dialog.
  2. Type xkill and press Enter.
  3. Your cursor will change to a crosshair. Click on the non-responsive window to kill it.

The xkill command is a part of the X Window System, which allows you to force close applications that are not responding. When you type xkill, it waits for you to click on a window, and then it kills the client that owns the window.

If you want to cancel an xkill command, simply right-click anywhere and the cursor will change back to the default arrow.

Creating a Keyboard Shortcut for xkill

For frequent issues with unresponsive applications, creating a keyboard shortcut for the xkill command can be a time-saver. Here’s how to do it:

  1. Type “keyboard” in the Unity Dash and click on the Keyboard icon. Go to the Shortcuts tab.
  2. Scroll down to the Custom Shortcuts section and click on the “+” button.
  3. Name your shortcut and set the command as xkill. Click OK.
  4. Click on the newly created shortcut and press the desired key combination to assign it.

Now, pressing the keyboard shortcut will activate xkill whenever you need it.

Using the System Monitor

The System Monitor is another tool you can use to kill unresponsive applications. Here’s how:

  1. Open the System Monitor by searching for it in the Unity Dash.
  2. Select the non-responsive process with the mouse and click the “End Process” button to kill it.

This method should work even with unresponsive processes. However, it may not be as strong as using kill -9.

Using a Script to Add a “Force Quit” Option to the Unity Launcher

If you prefer a GUI solution, you can add a “Force Quit” option to the Unity launcher by following the instructions in this article. This provides a GUI solution similar to the Activity Monitor in Mac OS X.

Using a Script to Send SIGTERM to the Currently Active Window

You can use the script provided in this GitHub repository to send SIGTERM to the currently active window. This script is based on a similar question on Unix & Linux Stack Exchange.

The SIGTERM signal allows the process to terminate gracefully. It is generally recommended to try kill PID first, which sends a SIGTERM signal, and only use kill -9 PID if the process does not respond to SIGTERM.


Dealing with unresponsive applications can be frustrating, but Unity provides several tools to handle this issue. Whether you prefer using commands like xkill, setting up keyboard shortcuts, using the System Monitor, or scripting, there’s a solution that will work for you. Remember to always be cautious when using the kill command, especially with the -9 option. Happy computing!

Can I use the `xkill` command in other desktop environments besides Unity?

Yes, the xkill command is not specific to Unity and can be used in other desktop environments that use the X Window System.

Will using the `xkill` command result in any data loss?

No, the xkill command simply terminates the unresponsive application. However, any unsaved data in the application may be lost, so it’s always recommended to save your work frequently.

Can I undo the action of using the `xkill` command?

No, once you use the xkill command and click on a window to kill it, the action cannot be undone. Therefore, it’s important to be cautious and make sure you are selecting the correct window before clicking.

Can I assign any keyboard shortcut for the `xkill` command?

Yes, you can assign any keyboard shortcut that is not already in use by another application or system function. However, it’s recommended to choose a keyboard shortcut that is easy to remember and won’t conflict with your workflow.

Is the System Monitor available in all Ubuntu versions?

Yes, the System Monitor is a built-in tool in Ubuntu and should be available in all versions of the operating system.

What should I do if the System Monitor fails to kill an unresponsive process?

If the System Monitor fails to kill an unresponsive process, you can try using the kill command with the -9 option in the terminal. However, be aware that this is a more forceful method and may result in data loss or other unintended consequences.

Can I use the script mentioned in the article on any Linux distribution?

Yes, the script provided in the article should work on any Linux distribution that uses the X Window System. However, it’s always a good idea to double-check compatibility and dependencies before using any script.

Is it safe to use the `kill -9` command to forcefully terminate a process?

Using the kill -9 command should be a last resort, as it forcefully terminates a process without allowing it to clean up or save any data. It’s generally recommended to try using kill without the -9 option first, to give the process a chance to terminate gracefully.

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