How To Setup Dual Monitors With XRandR: Step By Step

Setting up dual monitors with XRandR can be a straightforward process once you understand the basics. Here’s a step-by-step guide to help you configure your dual-monitor setup using XRandR.

Finding Your Monitors

The first step is to identify the names and capabilities of your monitors. You can do this by running the xrandr command in your terminal. This command will display a list of all available outputs, along with their supported resolutions and refresh rates.

xrandr

This output will show you the names of your monitors (e.g., HDMI-1, DP-1) and their current status. For example:

Screen 0: minimum 8 x 8, current 2560 x 1440, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
...

Setting Up Your Monitors

Once you know the names of your monitors, you can start configuring them. Here’s an example of how to set up two monitors with different resolutions:

xrandr --output DP-1 --primary --mode 1920x1080 --output HDMI-1 --mode 1360x768 --left-of DP-1

In this example:

• DP-1 is set as the primary monitor with a resolution of 1920x1080.
• HDMI-1 is set to the left of DP-1 with a resolution of 1360x768.

If you have another monitor that you want to display to the right, you can add it to the command like this:

xrandr --output DP-1 --primary --mode 1920x1080 --output HDMI-1 --mode 1360x768 --left-of DP-1 --output HDMI-2 --mode 1360x768 --right-of DP-1

Positioning and Scaling Monitors

If you need to position or scale your monitors, you can use additional options with xrandr. For example, to position a monitor at a specific location, you can use the --pos option:

xrandr --output HDMI-1 --mode 1920x1080 --pos 1920x0

This command sets the HDMI-1 monitor to a resolution of 1920x1080 and positions it at coordinates (1920, 0).

To scale monitors, especially useful when combining monitors of different resolutions, you can calculate the positions and sizes based on the resolutions and desired layout. For instance, if you want to scale a 1080p monitor to match a 4K monitor, you would need to calculate the positions and scaling factors accordingly.

Making Changes Persistent

To ensure that your monitor settings are applied every time you boot your system, you need to add the xrandr command to a startup script. One common method is to add it to your .xinitrc or .xsession file:

xrandr --output DP-1 --primary --mode 1920x1080 --output HDMI-1 --mode 1360x768 --left-of DP-1

Make sure there is no & at the end of the xrandr command, as it is not needed and could cause issues.

Troubleshooting Common Issues

Identifying Monitors

If you have multiple monitors connected via the same type of cable (e.g., two HDMI monitors), it can be tricky to identify which is which. A simple method is to turn off all but one monitor and then activate each one individually to determine their names.

Display Not Detected

If a monitor is not detected by xrandr, ensure that it is properly connected and recognized by your system. You can check the output of xrandr -q to see if the monitor is listed. If it is not, you may need to adjust your graphics settings or check for any hardware issues.

Persistent Settings Not Working

If your settings are not persisting across reboots, ensure that the xrandr command is correctly placed in your startup script and that there are no syntax errors. Also, verify that the script is being executed during startup.

By following these steps, you can effectively set up and manage your dual-monitor configuration using XRandR.