X Window System

The X Window System (X11) provides the basis of NixOS’ graphical user interface. It can be enabled as follows:

services.xserver.enable  = true;

The X server will automatically detect and use the appropriate video driver from a set of X.org drivers (such as vesa and intel). You can also specify a driver manually, e.g.

services.xserver.videoDrivers  = [ "r128" ];

to enable X.org’s xf86-video-r128 driver.

You also need to enable at least one desktop or window manager. Otherwise, you can only log into a plain undecorated xterm window. Thus you should pick one or more of the following lines:

services.xserver.desktopManager.plasma5.enable  = true;
services.xserver.desktopManager.xfce.enable  = true;
services.xserver.desktopManager.gnome3.enable  = true;
services.xserver.desktopManager.mate.enable  = true;
services.xserver.windowManager.xmonad.enable  = true;
services.xserver.windowManager.twm.enable  = true;
services.xserver.windowManager.icewm.enable  = true;
services.xserver.windowManager.i3.enable  = true;

NixOS’s default display manager (the program that provides a graphical login prompt and manages the X server) is LightDM. You can select an alternative one by picking one of the following lines:

services.xserver.displayManager.sddm.enable  = true;
services.xserver.displayManager.gdm.enable  = true;

You can set the keyboard layout (and optionally the layout variant):

services.xserver.layout  = "de";
services.xserver.xkbVariant  = "neo";

The X server is started automatically at boot time. If you don’t want this to happen, you can set:

services.xserver.autorun  = false;

The X server can then be started manually:

# systemctl start display-manager.service

On 64-bit systems, if you want OpenGL for 32-bit programs such as in Wine, you should also set the following:

hardware.opengl.driSupport32Bit  = true;

Auto-login

The x11 login screen can be skipped entirely, automatically logging you into your window manager and desktop environment when you boot your computer.

This is especially helpful if you have disk encryption enabled. Since you already have to provide a password to decrypt your disk, entering a second password to login can be redundant.

To enable auto-login, you need to define your default window manager and desktop environment. If you wanted no desktop environment and i3 as your your window manager, you’d define:

services.xserver.displayManager.defaultSession  = "none+i3";

Every display manager in NixOS supports auto-login, here is an example using lightdm for a user alice:

services.xserver.displayManager.lightdm.enable  = true;
services.xserver.displayManager.lightdm.autoLogin.enable  = true;
services.xserver.displayManager.lightdm.autoLogin.user  = "alice";

The options are named identically for all other display managers.

Proprietary NVIDIA drivers

NVIDIA provides a proprietary driver for its graphics cards that has better 3D performance than the X.org drivers. It is not enabled by default because it’s not free software. You can enable it as follows:

services.xserver.videoDrivers  = [ "nvidia" ];

Or if you have an older card, you may have to use one of the legacy drivers:

services.xserver.videoDrivers  = [ "nvidiaLegacy390" ];
services.xserver.videoDrivers  = [ "nvidiaLegacy340" ];
services.xserver.videoDrivers  = [ "nvidiaLegacy304" ];
services.xserver.videoDrivers  = [ "nvidiaLegacy173" ];

You may need to reboot after enabling this driver to prevent a clash with other kernel modules.

Proprietary AMD drivers

AMD provides a proprietary driver for its graphics cards that has better 3D performance than the X.org drivers. It is not enabled by default because it’s not free software. You can enable it as follows:

services.xserver.videoDrivers  = [ "ati_unfree" ];

You will need to reboot after enabling this driver to prevent a clash with other kernel modules.

Note

For recent AMD GPUs you most likely want to keep either the defaults or "amdgpu" (both free).

Touchpads

Support for Synaptics touchpads (found in many laptops such as the Dell Latitude series) can be enabled as follows:

services.xserver.libinput.enable  = true;

The driver has many options (see ch-options). For instance, the following disables tap-to-click behavior:

services.xserver.libinput.tapping  = false;

Note: the use of services.xserver.synaptics is deprecated since NixOS 17.09.

GTK/Qt themes

GTK themes can be installed either to user profile or system-wide (via environment.systemPackages). To make Qt 5 applications look similar to GTK2 ones, you can install qt5.qtbase.gtk package into your system environment. It should work for all Qt 5 library versions.

Custom XKB layouts

It is possible to install custom XKB keyboard layouts using the option . As a first example, we are going to create a layout based on the basic US layout, with an additional layer to type some greek symbols by pressing the right-alt key.

To do this we are going to create a us-greek file with a xkb_symbols section.

xkb_symbols "us-greek"
{
  include "us(basic)"            // includes the base US keys
  include "level3(ralt_switch)"  // configures right alt as a third level switch

  key <LatA> { [ a, A, Greek_alpha ] };
  key <LatB> { [ b, B, Greek_beta  ] };
  key <LatG> { [ g, G, Greek_gamma ] };
  key <LatD> { [ d, D, Greek_delta ] };
  key <LatZ> { [ z, Z, Greek_zeta  ] };
};

To install the layout, the filepath, a description and the list of languages must be given:

services.xserver.extraLayouts.us-greek = {
  description = "US layout with alt-gr greek";
  languages   = [ "eng" ];
  symbolsFile = /path/to/us-greek;
}

Note

The name should match the one given to the xkb_symbols block.

The layout should now be installed and ready to use: try it by running setxkbmap us-greek and type <alt>+a. To change the default the usual

option can still be used.

A layout can have several other components besides xkb_symbols, for example we will define new keycodes for some multimedia key and bind these to some symbol.

Use the xev utility from pkgs.xorg.xev to find the codes of the keys of interest, then create a media-key file to hold the keycodes definitions

xkb_keycodes "media"
{
 <volUp>   = 123;
 <volDown> = 456;
}

Now use the newly define keycodes in media-sym:

xkb_symbols "media"
{
 key.type = "ONE_LEVEL";
 key <volUp>   { [ XF86AudioLowerVolume ] };
 key <volDown> { [ XF86AudioRaiseVolume ] };
}

As before, to install the layout do

services.xserver.extraLayouts.media = {
  description  = "Multimedia keys remapping";
  languages    = [ "eng" ];
  symbolsFile  = /path/to/media-key;
  keycodesFile = /path/to/media-sym;
};

Note

The function pkgs.writeText <filename> <content> can be useful if you prefer to keep the layout definitions inside the NixOS configuration.

Unfortunately, the Xorg server does not (currently) support setting a keymap directly but relies instead on XKB rules to select the matching components (keycodes, types, …) of a layout. This means that components other than symbols won’t be loaded by default. As a workaround, you can set the keymap using setxkbmap at the start of the session with:

services.xserver.displayManager.sessionCommands  = "setxkbmap -keycodes media";

If you are manually starting the X server, you should set the argument -xkbdir /etc/X11/xkb, otherwise X won’t find your layout files. For example with xinit run

$ xinit -- -xkbdir /etc/X11/xkb

To learn how to write layouts take a look at the XKB documentation. More example layouts can also be found here.