Use cmd to launch programs (NixOS)

[MichaelBrunn3r]

I'm struggling to use the cmd action to launch applications. I tried tested multiple approaches with different applications, but none worked:

• mycmd (cmd wezterm): cmd executes the binary directly and has no PATH, so of course it doesn't know what wezterm is
• mycmd (cmd /run/current-system/sw/bin/wezterm): This way cmd finds the binary, but wezterm requires DISPLAY to be set: wezterm_gui > XOpenDisplay failed to open a display. Check the $DISPLAY env var; terminating
• mycmd (cmd /run/current-system/sw/bin/bash -c "DISPLAY=:0 /run/current-system/sw/bin/wezterm"): doesn't work either
• mycmd (cmd /run/current-system/sw/bin/bash -c "WAYLAND_DISPLAY=wayland-0 /run/current-system/sw/bin/wezterm"): nope

I tried other programs, but they either require DISPLAY to be set, or execute without any errors, but still don't open. How can I get this to work?

[MichaelBrunn3r]

I made some progress. It seems that NixOS hardened the configuration of the Kanata service to such an extend, that it is hardly usable to execute commands. Instead I defined my own service and set the required environment variables. Unfortunately this makes the config VERY non-portable. I will harden it step by step to find out what the minimum required permissions are.

systemd.services.kanata = {
  enable = true;
  unitConfig = {
    Description = "Kanata keyboard remapper";
    Documentation = "https://github.com/jtroo/kanata";
  };
  serviceConfig = let
    DISPLAY = "DISPLAY=:0";
    WAYLAND_DISPLAY = "WAYLAND_DISPLAY=wayland-0";
    XAUTHORITY = "XAUTHORITY=...";
    PATH = "PATH=...";
    XDG_RUNTIME_DIR = "XDG_RUNTIME_DIR=...";
  in {
    Type = "simple";
    User = "...";
    Environment = "${DISPLAY} ${WAYLAND_DISPLAY} ${XAUTHORITY} ${PATH} ${XDG_RUNTIME_DIR}";
    ExecStart = "/run/current-system/sw/bin/sh -c 'exec $$(which kanata) --cfg ${./config.kbd}'";
    Restart = "no";
  };
  wantedBy = ["default.target"];
};

[bbigras]

It seems that NixOS hardened the configuration of the Kanata service to such an extend, that it is hardly usable to execute commands.

Did you try services.kanata.package = kanata-with-cmd;?

[MichaelBrunn3r]

Oh, well this would have been an easy fix. Thx, I sometimes forget to search for these alternative packages. But this is a system-wide service only, right? In that case I think the home-manager solution is the better fit for me.

[MichaelBrunn3r]

Found an even better solution. I created the service using home-manager; that way I don't even have to setup the environment variables anymore. Another plus is, that other users can now use my PC without having to disable Kanata :D

home-manager.users.<user> = {config, ...}:
  with config; {
    systemd.user.services.kanata = {
      Unit = {
        Description = "Kanata keyboard remapper";
        Documentation = "https://github.com/jtroo/kanata";
      };
      Install = {
        WantedBy = ["default.target"];
      };
      Service = {
        Type = "notify";
        ExecStart = "/run/current-system/sw/bin/sh -c 'exec $$(which kanata) --cfg ${./config.kbd}'";
        Restart = "no";
      };
    };
  };