DisplayMode

DisplayMode is a command line tool for quickly showing and changing the current screen's resolution and refresh rate on X11, like xrandr(1). It has been designed for simplicity, and to accept non-integral refresh rates.

So here are the main differences to xrandr(1):

• DisplayMode accepts fractional refresh rates and finds the closest mode for it. For example: displaymode 29.97 will switch the refresh rate to 29.97 Hz.

• It's about resolution and refresh rate, none of the many additional features of xrandr(1) exist for DisplayMode. So it's much simpler.

Using DisplayMode

To show the current resolution and refreshrate, run displaymode without any parameters:

$ displaymode
Refresh rates for HDMI-A-1:
3840x2160@...    60      60      59.94   50      30      29.97   25      24      23.98

Refresh rates in bold are your display's default modes. The rate in italics will actually be shown as reverse text in reality, and it indicates the currently active refresh rate.

To switch to a different refresh rate, is simple:

$ displaymode 23.9

You might have noticed that the call says 23.9 there, but displaymode reported the rate as 23.98. That's fine, it'll switch to the closest available refresh rate.

To also change the display resolution, the call might be:

$ displaymode 1920x1080@60

The list of outputs (i.e. screens) is available with displaymode --list-outputs. If you have more than one active screen, displaymode works on the primary one by default; to have it work wit another screen use the -o parameter;

$ displaymode -o DisplayPort-0 60

That would switch the screen connected to the first DisplayPort interface to a refresh rate of 60 Hz.

To see all available resolutions and refresh rates, use displaymode --list-modes.

Building DisplayMode

DisplayMode consists of a single .cpp file, and it depends on Xlib and libxrandr. If you use Debian/Ubuntu or something similar, that means you need the libx11-dev and libxrandr-dev packages to be installed.

To build it, you may use cmake, or, because it's just a single file, just copy and paste this compiler call:

c++ -O2 displaymode.cpp -o displaymode -lX11 -lXrandr

Using cmake would look something like this:

$ cmake -DCMAKE_BUILD_TYPE=Release .
$ cmake --build .

License

DisplayMode is licensed under a MIT license. See LICENSE.txt for details.