Fixing xrandr can't open display Error: Quick Solutions

The xrandr command is a powerful tool for managing display settings on Linux systems. However, many users encounter the frustrating error message "can't open display" when trying to use it. This issue can arise due to various reasons, including incorrect display variable settings, missing permissions, or problems with the X Window System. In this article, we'll explore quick and effective solutions to resolve the xrandr can't open display error.

Understanding the Error

The “can’t open display” error typically occurs when the xrandr command is unable to connect to the X Window System, which is responsible for managing graphical displays on Linux. This error can manifest in different ways, such as:

• xrandr: unable to open display “”
• xrandr: cannot open display “”

To troubleshoot this issue, it’s essential to understand the underlying causes and identify the correct solution for your specific situation.

Solution 1: Check and Set the DISPLAY Variable

The DISPLAY environment variable is crucial for xrandr to function correctly. It specifies the display to which the command should connect. Here are the steps to check and set the DISPLAY variable:

Check the DISPLAY Variable

Open a terminal and run the following command:

echo $DISPLAY

If the variable is not set or is set incorrectly, you’ll need to set it manually.

Set the DISPLAY Variable

Set the DISPLAY variable using the following command, replacing :0 with the correct display number:

export DISPLAY=:0

Verify that the DISPLAY variable is set correctly by running echo $DISPLAY again.

Solution 2: Verify and Adjust Permissions

In some cases, the xrandr command may not have the necessary permissions to access the X Window System. To resolve this, you can try running the command with elevated privileges:

sudo xrandr

Alternatively, you can add your user to the x group, which typically has the necessary permissions:

sudo usermod -aG x $USER

Log out and log back in for the changes to take effect.

Solution 3: Ensure the X Window System is Running

The X Window System must be running for xrandr to function correctly. If you’re using a display manager like gdm, kdm, or sddm, ensure that it’s running and configured properly.

Check the X Window System Status

Use the following command to check the status of the X Window System:

systemctl status gdm

Replace gdm with the name of your display manager.

Restart the X Window System

If the X Window System is not running or is experiencing issues, try restarting it:

sudo systemctl restart gdm

Solution 4: Use the Correct xrandr Command Syntax

Ensure that you’re using the correct xrandr command syntax and options. For example, to list all available displays, use:

xrandr –listmonitors

Familiarize yourself with the various xrandr options and syntax to avoid errors.

Conclusion

Resolving the xrandr can’t open display error requires a systematic approach, focusing on the DISPLAY variable, permissions, X Window System configuration, and command syntax. By following these quick solutions, you should be able to troubleshoot and fix the issue efficiently.