### Install Gauge plugins with Nix

Source: https://nixos.org/manual/nixos/unstable/release-notes

Examples for loading Gauge plugins from a manifest file or defining them directly within Nix.

```nix
gauge.fromManifest ./path/to/manifest.json
```

```nix
gauge.withPlugins (p: with p; [ js html-report xml-report ])
```

--------------------------------

### Generate Mautrix-WhatsApp example configuration

Source: https://nixos.org/manual/nixos/unstable

Use this command to generate an example configuration file for comparison during migration.

```bash
nix-shell -p mautrix-whatsapp --run "mautrix-whatsapp -c example.yaml -e"
```

--------------------------------

### Defining configData examples

Source: https://nixos.org/manual/nixos/unstable

Example showing how to define configuration files using text content or source paths.

```nix
{
  "server.conf" = {
    text = ''
      port = 8080
      workers = 4
    '';
  };
  "ssl/cert.pem" = {
    source = ./cert.pem;
  };
}
```

--------------------------------

### Install Nix package manager

Source: https://nixos.org/manual/nixos/unstable

Execute the official installation script to set up Nix on the host system.

```shell
$ curl -L https://nixos.org/nix/install | sh
$ . $HOME/.nix-profile/etc/profile.d/nix.sh # …or open a fresh shell
```

--------------------------------

### Execute NixOS installation

Source: https://nixos.org/manual/nixos/unstable

Run the installation command to build and install the NixOS system.

```shell
$ sudo PATH="$PATH" `which nixos-install` --root /mnt
```

--------------------------------

### Install NixOS on /dev/sda

Source: https://nixos.org/manual/nixos/unstable

A complete sequence of commands to format, mount, and install NixOS.

```bash
# mkfs.ext4 -L nixos /dev/sda1
# mkswap -L swap /dev/sda2
# swapon /dev/sda2
# mkfs.fat -F 32 -n boot /dev/sda3        # (for UEFI systems only)
# mount /dev/disk/by-label/nixos /mnt
# mkdir -p /mnt/boot                      # (for UEFI systems only)
# mount -o umask=077 /dev/disk/by-label/boot /mnt/boot # (for UEFI systems only)
# nixos-generate-config --root /mnt
# nano /mnt/etc/nixos/configuration.nix
# nixos-install
# reboot
```

--------------------------------

### Start X server with custom XKB directory

Source: https://nixos.org/manual/nixos/unstable

Specify the XKB directory when manually starting the X server to ensure custom files are found.

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

--------------------------------

### Enter NixOS Installation Shell

Source: https://nixos.org/manual/nixos/unstable

Commands to start a login shell within a NixOS installation located at /mnt.

```bash
$ nix-build '<nixpkgs>' -A nixos-enter
# ./result/bin/nixos-enter
```

--------------------------------

### Configure extraPythonPackages example

Source: https://nixos.org/manual/nixos/unstable

Example usage for adding Python packages to the test driver.

```nix
p: [ p.numpy ]
```

--------------------------------

### Configure enableDebugHook example

Source: https://nixos.org/manual/nixos/unstable

Example value for enabling the debug hook.

```nix
true
```

--------------------------------

### Start X server manually

Source: https://nixos.org/manual/nixos/unstable

Command to start the display manager service manually.

```bash
# systemctl start display-manager.service
```

--------------------------------

### Install NixOS tools

Source: https://nixos.org/manual/nixos/unstable

Install the necessary tools for NixOS installation, such as nixos-install and nixos-generate-config.

```shell
$ nix-env -f '<nixpkgs>' -iA nixos-install-tools
```

--------------------------------

### NixOS configuration example

Source: https://nixos.org/manual/nixos/unstable

A sample configuration file demonstrating imports, bootloader settings, and service enablement.

```nix
{ config, pkgs, ... }: {
  imports = [
    # Include the results of the hardware scan.
    ./hardware-configuration.nix
  ];

  boot.loader.grub.device = "/dev/sda";   # (for BIOS systems only)
  boot.loader.systemd-boot.enable = true; # (for UEFI systems only)

  # Note: setting fileSystems is generally not
  # necessary, since nixos-generate-config figures them out
  # automatically in hardware-configuration.nix.
  #fileSystems."/" .device = "/dev/disk/by-label/nixos";

  # Enable the OpenSSH server.
  services.sshd.enable = true;
}
```

--------------------------------

### Execute NixOS installation

Source: https://nixos.org/manual/nixos/unstable

Run the standard installation command or use the flake-based variant for custom configurations.

```bash
# nixos-install
```

```bash
# nixos-install --flake 'path/to/flake.nix#nixos'
```

--------------------------------

### Start a NixOS container

Source: https://nixos.org/manual/nixos/unstable

Boots the specified container and waits until it reaches multi-user.target.

```bash
# nixos-container start foo
```

--------------------------------

### Activate and start Emacs service

Source: https://nixos.org/manual/nixos/unstable

Commands to apply the configuration and start the Emacs daemon.

```bash
$ nixos-rebuild switch  # to activate the new configuration.nix
$ systemctl --user daemon-reload        # to force systemd reload
$ systemctl --user start emacs.service  # to start the Emacs daemon
```

--------------------------------

### Install NixOS Bootloader on UEFI Systems

Source: https://nixos.org/manual/nixos/unstable

Backs up existing boot files and triggers the NixOS bootloader installation.

```bash
$ sudo mkdir /boot.bak && sudo mv /boot/* /boot.bak &&
sudo NIXOS_INSTALL_BOOTLOADER=1 /nix/var/nix/profiles/system/bin/switch-to-configuration boot
```

--------------------------------

### Add package to systemPackages

Source: https://nixos.org/manual/nixos/unstable

Example of adding a custom package to the system configuration.

```nix
{ environment.systemPackages = [ pkgs.my-package ]; }
```

--------------------------------

### Define a Modular Service Instance

Source: https://nixos.org/manual/nixos/unstable

Example of configuring a service instance by importing a module into system.services.

```nix
{
  system.services.my-service-instance = {
    imports = [ pkgs.some-application.services.some-service-module ];
    foo.settings = {
      # ...
    };
  };
}
```

--------------------------------

### Install a package with nix-env

Source: https://nixos.org/manual/nixos/unstable

Installs a package by its attribute name. Using the -A flag is recommended for performance and to avoid ambiguity.

```bash
$ nix-env -iA nixos.thunderbird
```

--------------------------------

### Build and install NixOS system profile

Source: https://nixos.org/manual/nixos/unstable

Installs the NixOS system closure into the system profile using the specified configuration file.

```bash
$ nix-env -p /nix/var/nix/profiles/system -f '<nixpkgs/nixos>' -I nixos-config=/etc/nixos/configuration.nix -iA system
```

--------------------------------

### Defining Configuration Options

Source: https://nixos.org/manual/nixos/unstable

Example of setting service options using dot notation for nested sets.

```nix
{ config, pkgs, ... }:

{
  services.httpd.enable = true;
  services.httpd.adminAddr = "alice@example.org";
  services.httpd.virtualHosts.localhost.documentRoot = "/webroot";
}
```

```nix
{ config, pkgs, ... }:

{
  services = {
    httpd = {
      enable = true;
      adminAddr = "alice@example.org";
      virtualHosts = {
        localhost = {
          documentRoot = "/webroot";
        };
      };
    };
  };
}
```

--------------------------------

### Configure VirtualBox bootloader

Source: https://nixos.org/manual/nixos/unstable

Enable GRUB bootloader for a VirtualBox guest installation.

```nix
{ boot.loader.grub.device = "/dev/sda"; }
```

--------------------------------

### Mount Installation Targets

Source: https://nixos.org/manual/nixos/unstable

Mounting the root and boot filesystems to the /mnt directory.

```bash
# mount /dev/disk/by-label/nixos /mnt
```

```bash
# mkdir -p /mnt/boot
# mount -o umask=077 /dev/disk/by-label/boot /mnt/boot
```

--------------------------------

### Start GitLab manual backup

Source: https://nixos.org/manual/nixos/unstable

Executes a manual backup of the GitLab instance using systemd.

```bash
$ systemctl start gitlab-backup.service
```

--------------------------------

### Enable OneDrive Service

Source: https://nixos.org/manual/nixos/unstable

Add this option to your configuration.nix to install the onedrive package and launcher service.

```nix
services.onedrive.enable = true;
```

--------------------------------

### Initialize NIXOS and NIXOS_LUSTRATE files

Source: https://nixos.org/manual/nixos/unstable

Creates the required marker files to identify the partition as NixOS and enable the lustrate process.

```bash
$ sudo touch /etc/NIXOS
$ sudo touch /etc/NIXOS_LUSTRATE
```

--------------------------------

### Configure Synapse on NixOS

Source: https://nixos.org/manual/nixos/unstable

A complete NixOS configuration example for a Synapse homeserver, including Nginx virtual host setup for well-known discovery and proxying.

```nix
{
  pkgs,
  lib,
  config,
  ...
}:
let
  fqdn = "${config.networking.hostName}.${config.networking.domain}";
  baseUrl = "https://${fqdn}";
  clientConfig."m.homeserver".base_url = baseUrl;
  serverConfig."m.server" = "${fqdn}:443";
  mkWellKnown = data: ''
    default_type application/json;
    add_header Access-Control-Allow-Origin *;
    return 200 '${builtins.toJSON data}';
  '';
in
{
  networking.hostName = "myhostname";
  networking.domain = "example.org";
  networking.firewall.allowedTCPPorts = [
    80
    443
  ];

  services.postgresql.enable = true;

  services.nginx = {
    enable = true;
    recommendedTlsSettings = true;
    recommendedOptimisation = true;
    recommendedGzipSettings = true;
    recommendedProxySettings = true;
    virtualHosts = {
      # If the A and AAAA DNS records on example.org do not point on the same host as the
      # records for myhostname.example.org, you can easily move the /.well-known
      # virtualHost section of the code to the host that is serving example.org, while
      # the rest stays on myhostname.example.org with no other changes required.
      # This pattern also allows to seamlessly move the homeserver from
      # myhostname.example.org to myotherhost.example.org by only changing the
      # /.well-known redirection target.
      "${config.networking.domain}" = {
        enableACME = true;
        forceSSL = true;
        # This section is not needed if the server_name of matrix-synapse is equal to
        # the domain (i.e. example.org from @foo:example.org) and the federation port
        # is 8448.
        # Further reference can be found in the docs about delegation under
        # https://element-hq.github.io/synapse/latest/delegate.html
        locations."= /.well-known/matrix/server".extraConfig = mkWellKnown serverConfig;
        # This is usually needed for homeserver discovery (from e.g. other Matrix clients).
        # Further reference can be found in the upstream docs at
        # https://spec.matrix.org/latest/client-server-api/#getwell-knownmatrixclient
        locations."= /.well-known/matrix/client".extraConfig = mkWellKnown clientConfig;
      };
      "${fqdn}" = {
        enableACME = true;
        forceSSL = true;
        # It's also possible to do a redirect here or something else, this vhost is not
        # needed for Matrix. It's recommended though to *not put* element
        # here, see also the section about Element.
        locations."/".extraConfig = ''
          return 404;
        '';
        # Forward all Matrix API calls to the synapse Matrix homeserver. A trailing slash
        # *must not* be used here.
        locations."/_matrix".proxyPass = "http://[::1]:8008";
        # Forward requests for e.g. SSO and password-resets.
        locations."/_synapse/client".proxyPass = "http://[::1]:8008";
      };
    };
  };

  services.matrix-synapse = {
    enable = true;
    settings.server_name = config.networking.domain;
    # The public base URL value must match the `base_url` value set in `clientConfig` above.
    # The default value here is based on `server_name`, so if your `server_name` is different
    # from the value of `fqdn` above, you will likely run into some mismatched domain names
    # in client applications.
    settings.public_baseurl = baseUrl;
    settings.listeners = [
      {
        port = 8008;
        bind_addresses = [ "::1" ];
        type = "http";
        tls = false;
        x_forwarded = true;
        resources = [
          {
            names = [
              "client"
              "federation"
            ];
            compress = true;
          }
        ];
      }
    ];
  };
}

```

--------------------------------

### Build and test kernel and initial ramdisk

Source: https://nixos.org/manual/nixos/unstable

Build the kernel and initrd components and test them using QEMU.

```bash
$ nix-build -A config.system.build.initialRamdisk -o initrd
$ nix-build -A config.system.build.kernel -o kernel
$ qemu-system-x86_64 -kernel ./kernel/bzImage -initrd ./initrd/initrd -hda /dev/null
```

--------------------------------

### Test the NixOS Installer

Source: https://nixos.org/manual/nixos/unstable

Commands to verify the installer functionality by mounting a tmpfs and running the installation process.

```bash
# mount -t tmpfs none /mnt
# nixos-generate-config --root /mnt
$ nix-build '<nixpkgs>' -A nixos-install
# ./result/bin/nixos-install
```

--------------------------------

### Manual window manager startup in .xinitrc

Source: https://nixos.org/manual/nixos/unstable

Example commands to launch window managers when managing the xinitrc file manually.

```bash
sxhkd &
bspwm &
```

--------------------------------

### meta.teams example

Source: https://nixos.org/manual/nixos/unstable

Example of defining teams for a module.

```nix
[ lib.teams.acme lib.teams.haskell ]
```

--------------------------------

### Enable manual X server startup

Source: https://nixos.org/manual/nixos/unstable

Configures the system to allow starting the X server manually via the startx command.

```nix
{
  services.xserver.displayManager.startx = {
    enable = true;
    generateScript = true;
  };
}
```

--------------------------------

### meta.maintainers example

Source: https://nixos.org/manual/nixos/unstable

Example of defining maintainers for a module.

```nix
[ lib.maintainers.alice lib.maintainers.bob ]
```

--------------------------------

### Breakpoint output example

Source: https://nixos.org/manual/nixos/unstable

Example output displayed when a test breakpoint is reached.

```text
vm-test-run-foo> !!! Breakpoint reached, run 'sudo /nix/store/eeeee-attach/bin/attach <PID>'
```

--------------------------------

### Build kexec files

Source: https://nixos.org/manual/nixos/unstable

Build the necessary kernel, initrd, and boot script from the current nixpkgs version.

```bash
nix-build -A kexec.x86_64-linux '<nixpkgs/nixos/release.nix>'
```

--------------------------------

### Build netboot images

Source: https://nixos.org/manual/nixos/unstable

Build the necessary files for PXE or iPXE booting from the current nixpkgs version.

```bash
nix-build -A netboot.x86_64-linux '<nixpkgs/nixos/release.nix>'
```

--------------------------------

### Build configuration reference manpage

Source: https://nixos.org/manual/nixos/unstable

Commands to build and view the configuration.nix man page.

```bash
$ cd /path/to/nixpkgs
$ nix-build nixos/release.nix -A nixos-configuration-reference-manpage.x86_64-linux
```

```bash
$ man --local-file result/share/man/man5/configuration.nix.5
```

--------------------------------

### Set root password

Source: https://nixos.org/manual/nixos/unstable

The installer prompts for a root password during the final installation phase.

```text
setting root password...
New password: ***
Retype new password: ***
```

--------------------------------

### Install Haskell programs

Source: https://nixos.org/manual/nixos/unstable/release-notes

Install specific Haskell executables using the nix-env command.

```bash
nix-env -f "<nixpkgs>" -iA haskellPackages.pandoc
```

--------------------------------

### Test Configuration in VM

Source: https://nixos.org/manual/nixos/unstable

Builds and runs the configuration in a QEMU virtual machine.

```bash
$ nixos-rebuild build-vm
$ ./result/bin/run-*-vm
```

--------------------------------

### Example configuration with custom position

Source: https://nixos.org/manual/nixos/unstable

Demonstrates how custom file locations appear in error messages when definition conflicts occur.

```nix
{
  _file = "file.nix";
  options.foo = mkOption { default = 13; };
  config.foo = lib.mkDefinition {
    file = "custom place";
    # mkOptionDefault creates a conflict with the option foo's `default = 1` on purpose
    # So we see the error message below contains the conflicting values and different positions
    value = lib.mkOptionDefault 42;
  };
}
```

--------------------------------

### Start interactive shell after filesystem mounting

Source: https://nixos.org/manual/nixos/unstable

Starts an interactive shell after all initrd filesystems are mounted.

```text
boot.debug1mounts
```

--------------------------------

### Format Partitions

Source: https://nixos.org/manual/nixos/unstable

Commands to initialize filesystems and swap partitions with labels for device independence.

```bash
# mkfs.ext4 -L nixos /dev/sda1
```

```bash
# mkswap -L swap /dev/sda2
```

```bash
# mkfs.fat -F 32 -n boot /dev/sda3
```

--------------------------------

### Configure system.nix as an alternative entry point

Source: https://nixos.org/manual/nixos/unstable/release-notes

Use this file to configure NixOS without relying on nix-channel by pinning a specific Nixpkgs version.

```nix
# system.nix
let
  # Pinned Nixpkgs archive
  #
  # Use `curl -I https://channels.nixos.org/nixos-26.05` to get the
  # latest commit of the stable channel and `nix-prefetch-url --unpack`
  # to compute its sha256 hash.
  nixpkgs = builtins.fetchTarball {
    url = "https://github.com/NixOS/nixpkgs/archive/c217913993d6.tar.gz";
    sha256 = "026mprs324330pfazlgbw987qmsa8ligglarvqbcxzig2kgw0lqg";
  };
in
import "${nixpkgs}/nixos" {
  # Build NixOS using an external configuration.nix file,
  # or directly set your options here
  configuration = ./configuration.nix;
}
```

--------------------------------

### Configure qemu.package

Source: https://nixos.org/manual/nixos/unstable

Default QEMU package used for virtualisation.

```nix
"hostPkgs.qemu_test"
```

--------------------------------

### Start interactive shell in stage 1

Source: https://nixos.org/manual/nixos/unstable

Starts an interactive shell before modules are loaded or filesystems are mounted.

```text
boot.debug1
```

--------------------------------

### Migrate Keycloak Configuration

Source: https://nixos.org/manual/nixos/unstable/release-notes

Example showing the transition from the deprecated Keycloak configuration options to the new settings-style format.

```nix
{
  services.keycloak = {
    enable = true;
    httpPort = "8080";
    frontendUrl = "https://keycloak.example.com/auth";
    database.passwordFile = "/run/keys/db_password";
    extraConfig = {
      "subsystem=undertow"."server=default-server"."http-listener=default".proxy-address-forwarding =
        true;
    };
  };
}
```

```nix
{
  services.keycloak = {
    enable = true;
    settings = {
      http-port = 8080;
      hostname = "keycloak.example.com";
      http-relative-path = "/auth";
      proxy = "edge";
    };
    database.passwordFile = "/run/keys/db_password";
  };
}
```

--------------------------------

### Install NixOS Bootloader

Source: https://nixos.org/manual/nixos/unstable

Triggers the NixOS bootloader installation for systems where the EFI partition is already correctly mounted.

```bash
sudo NIXOS_INSTALL_BOOTLOADER=1 /nix/var/nix/profiles/system/bin/switch-to-configuration boot
```

--------------------------------

### Configure permissions in postStart

Source: https://nixos.org/manual/nixos/unstable

Grant database permissions using the postStart hook of the postgresql-setup service.

```nix
{
  systemd.services.postgresql-setup.postStart = ''
    psql service1 -c 'GRANT SELECT ON ALL TABLES IN SCHEMA public TO "extraUser1"'
    psql service1 -c 'GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO "extraUser1"'
    # ....
  '';
}
```

--------------------------------

### Configure basic Nextcloud instance

Source: https://nixos.org/manual/nixos/unstable

A minimal configuration enabling Nextcloud with a local PostgreSQL database and required firewall ports.

```nix
{ pkgs, ... }:
{
  services.nextcloud = {
    enable = true;
    hostName = "nextcloud.tld";
    database.createLocally = true;
    config = {
      dbtype = "pgsql";
      adminpassFile = "/path/to/admin-pass-file";
    };
  };

  networking.firewall.allowedTCPPorts = [
    80
    443
  ];
}
```

--------------------------------

### Configure additional drivers in NixOS installer

Source: https://nixos.org/manual/nixos/unstable

Extends the graphical GNOME installer configuration to include Broadcom WiFi drivers.

```nix
{ config, ... }:

{
  imports = [ ./installation-cd-graphical-gnome.nix ];

  boot.initrd.kernelModules = [ "wl" ];

  boot.kernelModules = [
    "kvm-intel"
    "wl"
  ];
  boot.extraModulePackages = [ config.boot.kernelPackages.broadcom_sta ];
}
```

--------------------------------

### Markup command arguments in examples

Source: https://nixos.org/manual/nixos/unstable

Example of using mdoc macros to differentiate commands and arguments within a descriptive sentence.

```mdoc
This will run
.Ic ssh Ar name Ic time
to retrieve the remote time.

```

--------------------------------

### Start interactive shell after device initialization

Source: https://nixos.org/manual/nixos/unstable

Starts an interactive shell after kernel modules are loaded and device nodes are created.

```text
boot.debug1devices
```

--------------------------------

### Construct a NixOS system from a Nixpkgs invocation

Source: https://nixos.org/manual/nixos/unstable/release-notes

Demonstrates how to construct a NixOS system using a preexisting Nixpkgs invocation to improve evaluation performance.

```nix
{
  inherit
    (pkgs.nixos {
      boot.loader.grub.enable = false;
      fileSystems."/".device = "/dev/xvda1";
    })
    toplevel
    kernel
    initialRamdisk
    manual
    ;
}
```

--------------------------------

### GET /image/original/{file}

Source: https://nixos.org/manual/nixos/unstable

Retrieves a full-resolution image.

```APIDOC
## GET /image/original/{file}

### Description
Retrieves a full-resolution image.

### Method
GET

### Endpoint
/image/original/{file}

### Parameters
#### Path Parameters
- **file** (string) - Required - The filename of the image
```

--------------------------------

### Create a Subversion repository

Source: https://nixos.org/manual/nixos/unstable

Initialize a new repository using the svn command.

```bash
$ svn create REPO_NAME
```

--------------------------------

### GET /image/download

Source: https://nixos.org/manual/nixos/unstable

Downloads an image from a remote server.

```APIDOC
## GET /image/download

### Description
Download an image from a remote server, returning the same JSON payload as the POST /image endpoint.

### Method
GET

### Endpoint
/image/download

### Parameters
#### Query Parameters
- **url** (string) - Required - The URL of the image to download
```

--------------------------------

### Configure Kodi Addons in NixOS

Source: https://nixos.org/manual/nixos/unstable/release-notes

Demonstrates the transition from legacy configuration flags to the new withPackages approach for managing Kodi addons.

```nix
{
  environment.systemPackages = [ pkgs.kodi ];

  nixpkgs.config.kodi = {
    enableInputStreamAdaptive = true;
    enableVFSSFTP = true;
  };
}
```

```nix
{
  environment.systemPackages = [
    (pkgs.kodi.withPackages (
      p: with p; [
        inputstream-adaptive
        vfs-sftp
      ]
    ))
  ];
}
```

--------------------------------

### Enable GNOME Games

Source: https://nixos.org/manual/nixos/unstable

Installs the collection of GNOME games.

```nix
{ services.gnome.games.enable = true; }
```

--------------------------------

### Define requiredFeatures

Source: https://nixos.org/manual/nixos/unstable

Example configuration for required builder features.

```nix
{
  cuda = true;
  devnet = mkForce false;
}
```

```nix
{ }
```

--------------------------------

### Build the NixOS Manual

Source: https://nixos.org/manual/nixos/unstable

Build the manual using nix-build to generate HTML documentation.

```bash
nix-build nixos/release.nix -A manual.x86_64-linux
```

--------------------------------

### GET /image/details/original/{file}

Source: https://nixos.org/manual/nixos/unstable

Retrieves metadata for a full-resolution image.

```APIDOC
## GET /image/details/original/{file}

### Description
Retrieves the details of a full-resolution image.

### Method
GET

### Endpoint
/image/details/original/{file}

### Response
#### Success Response (200)
- **width** (int) - Image width
- **height** (int) - Image height
- **content_type** (string) - MIME type
- **created_at** (array) - Creation timestamp data
```

--------------------------------

### Initialize Pleroma Database

Source: https://nixos.org/manual/nixos/unstable

Seed the database using the generated setup.psql file.

```bash
$ sudo -u postgres psql -f setup.psql
```

--------------------------------

### Build the top-level system

Source: https://nixos.org/manual/nixos/unstable

A shortcut command to build the entire NixOS system configuration.

```bash
$ nix-build -A system
```

--------------------------------

### Reboot system

Source: https://nixos.org/manual/nixos/unstable

Final command to restart the machine after a successful installation.

```bash
# reboot
```

--------------------------------

### Access root shell

Source: https://nixos.org/manual/nixos/unstable

Elevate privileges to root in the installer environment.

```bash
$ sudo -i
```

--------------------------------

### GET /image/process.{ext}

Source: https://nixos.org/manual/nixos/unstable

Retrieves an image with specified transformations applied.

```APIDOC
## GET /image/process.{ext}

### Description
Get a file with transformations applied. Supported extensions include png, jpg, and webp.

### Method
GET

### Endpoint
/image/process.{ext}

### Parameters
#### Path Parameters
- **ext** (string) - Required - The desired file extension

#### Query Parameters
- **src** (string) - Required - The source filename
- **identity** (boolean) - Optional - Apply no changes
- **blur** (float) - Optional - Apply a gaussian blur
- **thumbnail** (int) - Optional - Produce a thumbnail
- **resize** (int) - Optional - Produce a thumbnail using Lanczos2 filter
- **crop** (string) - Optional - Crop with specified aspect ratio (e.g., 1600x900)
```

--------------------------------

### Configure prebuilt Mattermost plugins

Source: https://nixos.org/manual/nixos/unstable

Use fetchurl to provide a plugin tarball to the services.mattermost.plugins list. Ensure the tarball remains packed as the NixOS module handles the unpacking process.

```nix
{
  services.mattermost = {
    plugins = with pkgs; [
      # todo
      # 0.7.1
      # https://github.com/mattermost/mattermost-plugin-todo/releases/tag/v0.7.1
      (fetchurl {
        # Note: Don't unpack the tarball; the NixOS module will repack it for you.
        url = "https://github.com/mattermost-community/mattermost-plugin-todo/releases/download/v0.7.1/com.mattermost.plugin-todo-0.7.1.tar.gz";
        hash = "sha256-P+Z66vqE7FRmc2kTZw9FyU5YdLLbVlcJf11QCbfeJ84=";
      })
    ];
  };
}
```

--------------------------------

### Configuring filesystem options

Source: https://nixos.org/manual/nixos/unstable/release-notes

Filesystem options must now be provided as a list of strings instead of a comma-separated string.

```nix
{
  fileSystems."/example" = {
    device = "/dev/sdc";
    fsType = "btrfs";
    options = [
      "noatime"
      "compress=lzo"
      "space_cache"
      "autodefrag"
    ];
  };
}
```

--------------------------------

### Manage Flatpak Applications

Source: https://nixos.org/manual/nixos/unstable

Commands for searching, installing, and executing Flatpak applications.

```bash
$ flatpak search bustle
$ flatpak install flathub org.freedesktop.Bustle
$ flatpak run org.freedesktop.Bustle
```

--------------------------------

### Disable Pantheon Default Apps

Source: https://nixos.org/manual/nixos/unstable

Prevents the installation of default Pantheon applications.

```nix
{ services.pantheon.apps.enable = false; }
```

--------------------------------

### Apply System Configuration

Source: https://nixos.org/manual/nixos/unstable

Commands to build and activate system configurations. Requires root privileges.

```bash
# nixos-rebuild switch
```

```bash
# nixos-rebuild test
```

```bash
# nixos-rebuild boot
```

```bash
# nixos-rebuild switch -p test
```

--------------------------------

### Disable GNOME Core Apps

Source: https://nixos.org/manual/nixos/unstable

Prevents the installation of GNOME core applications.

```nix
{ services.gnome.core-apps.enable = false; }
```

--------------------------------

### Build the NixOS manual

Source: https://nixos.org/manual/nixos/unstable

Commands to navigate to the nixpkgs directory, edit the manual, and build the documentation using nix-build.

```bash
$ cd /path/to/nixpkgs
$ $EDITOR nixos/doc/manual/... # edit the manual
$ nix-build nixos/release.nix -A manual.x86_64-linux
```

--------------------------------

### Print Default Configuration

Source: https://nixos.org/manual/nixos/unstable

Runs the mautrix-discord binary to output the default configuration file.

```bash
nix-shell -p mautrix-discord --run "mautrix-discord -e"
```

--------------------------------

### Configure Akkoma media previews

Source: https://nixos.org/manual/nixos/unstable

Enable and set dimensions for generated media previews.

```nix
{
  services.akkoma.config.":pleroma".":media_preview_proxy" = {
    enabled = true;
    thumbnail_max_width = 1920;
    thumbnail_max_height = 1080;
  };
}
```

--------------------------------

### Enable unfree packages

Source: https://nixos.org/manual/nixos/unstable/release-notes

Explicitly allow the installation of packages with unfree licenses.

```nix
{ nixpkgs.config.allowUnfree = true; }
```