[[ch-installation]]
== Installing Home Manager

:nix-darwin: https://github.com/LnL7/nix-darwin/
:nixos-wiki-flakes: https://nixos.wiki/wiki/Flakes

Home Manager can be used in three primary ways:

1. Using the standalone `home-manager` tool. For platforms other than
NixOS and Darwin, this is the only available choice. It is also
recommended for people on NixOS or Darwin that want to manage their
home directory independently of the system as a whole. See
<<sec-install-standalone>> for instructions on how to perform this
installation.

2. As a module within a NixOS system configuration. This allows the
user profiles to be built together with the system when running
`nixos-rebuild`. See <<sec-install-nixos-module>> for a description of
this setup.

3. As a module within a {nix-darwin}[nix-darwin] system configuration.
This allows the user profiles to be built together with the system
when running `darwin-rebuild`. See <<sec-install-nix-darwin-module>>
for a description of this setup.

[NOTE]
In this chapter we describe how to install Home Manager in the
standard way using channels. If you prefer to use
{nixos-wiki-flakes}[Nix Flakes] then please see the instructions in
<<ch-nix-flakes>>.

[[sec-install-standalone]]
=== Standalone installation

:nix-allowed-users: https://nixos.org/nix/manual/#conf-allowed-users
:nixos-allowed-users: https://nixos.org/manual/nixos/stable/options.html#opt-nix.settings.allowed-users
:bash: https://www.gnu.org/software/bash/
:zsh: http://zsh.sourceforge.net/
:fish: https://fishshell.com
:plugin-foreign-env: https://github.com/oh-my-fish/plugin-foreign-env
:babelfish: https://github.com/bouk/babelfish

1. Make sure you have a working Nix installation. Specifically, make
sure that your user is able to build and install Nix packages. For
example, you should be able to successfully run a command like
`nix-instantiate '<nixpkgs>' -A hello` without having to switch to the
root user. For a multi-user install of Nix this means that your user
must be covered by the {nix-allowed-users}[`allowed-users`] Nix
option. On NixOS you can control this option using the
{nixos-allowed-users}[`nix.settings.allowed-users`] system option.

2. Add the appropriate Home Manager channel. If you are following
Nixpkgs master or an unstable channel you can run
+
[source,console]
----
$ nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
$ nix-channel --update
----
+
and if you follow a Nixpkgs version 23.05 channel you can run
+
[source,console]
----
$ nix-channel --add https://github.com/nix-community/home-manager/archive/release-23.05.tar.gz home-manager
$ nix-channel --update
----

3. Run the Home Manager installation command and create the first Home
Manager generation:
+
[source,console]
$ nix-shell '<home-manager>' -A install
+
Once finished, Home Manager should be active and available in your
user environment.

4. If you do not plan on having Home Manager manage your shell
configuration then you must source the
+
[source,bash]
$HOME/.nix-profile/etc/profile.d/hm-session-vars.sh
+
file in your shell configuration. Alternatively source
+
[source,bash]
/etc/profiles/per-user/$USER/etc/profile.d/hm-session-vars.sh
+
when managing home configuration together with system configuration.
+
This file can be sourced directly by POSIX.2-like shells such as
{bash}[Bash] or {zsh}[Z shell]. {fish}[Fish] users can use utilities
such as {plugin-foreign-env}[foreign-env] or {babelfish}[babelfish].
+
For example, if you use Bash then add
+
[source,bash]
----
. "$HOME/.nix-profile/etc/profile.d/hm-session-vars.sh"
----
+
to your `~/.profile` file.

If instead of using channels you want to run Home Manager from a Git
checkout of the repository then you can use the
<<opt-programs.home-manager.path>> option to specify the absolute path
to the repository.

Once installed you can see <<ch-usage>> for a more detailed
description of Home Manager and how to use it.

[[sec-install-nixos-module]]
=== NixOS module

Home Manager provides a NixOS module that allows you to prepare user
environments directly from the system configuration file, which often
is more convenient than using the `home-manager` tool. It also opens
up additional possibilities, for example, to automatically configure
user environments in NixOS declarative containers or on systems
deployed through NixOps.

To make the NixOS module available for use you must `import` it into
your system configuration. This is most conveniently done by adding a
Home Manager channel to the root user. For example, if you are
following Nixpkgs master or an unstable channel, you can run

[source,console]
----
$ sudo nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
$ sudo nix-channel --update
----

and if you follow a Nixpkgs version 23.05 channel, you can run

[source,console]
----
$ sudo nix-channel --add https://github.com/nix-community/home-manager/archive/release-23.05.tar.gz home-manager
$ sudo nix-channel --update
----

It is then possible to add

[source,nix]
imports = [ <home-manager/nixos> ];

to your system `configuration.nix` file, which will introduce a new
NixOS option called `home-manager.users` whose type is an attribute
set that maps user names to Home Manager configurations.

For example, a NixOS configuration may include the lines

[source,nix]
----
users.users.eve.isNormalUser = true;
home-manager.users.eve = { pkgs, ... }: {
  home.packages = [ pkgs.atool pkgs.httpie ];
  programs.bash.enable = true;

  # The state version is required and should stay at the version you
  # originally installed.
  home.stateVersion = "23.05";
};
----

and after a `sudo nixos-rebuild switch` the user eve's environment should
include a basic Bash configuration and the packages atool and httpie.

[NOTE]
====
If `nixos-rebuild switch` does not result in the environment you expect,
you can take a look at the output of the Home Manager activation script output using

[source,console]
$ systemctl status "home-manager-$USER.service"
====

If you do not plan on having Home Manager manage your shell
configuration then you must add either

[source,bash]
----
. "$HOME/.nix-profile/etc/profile.d/hm-session-vars.sh"
----

or

[source,bash]
----
. "/etc/profiles/per-user/$USER/etc/profile.d/hm-session-vars.sh"
----

to your shell configuration, depending on whether
<<nixos-opt-home-manager.useUserPackages>> is enabled. This file can
be sourced directly by POSIX.2-like shells such as {bash}[Bash] or
{zsh}[Z shell]. {fish}[Fish] users can use utilities such as
{plugin-foreign-env}[foreign-env] or {babelfish}[babelfish].

[NOTE]
====
By default packages will be installed to `$HOME/.nix-profile` but they
can be installed to `/etc/profiles` if

[source,nix]
home-manager.useUserPackages = true;

is added to the system configuration. This is necessary if, for
example, you wish to use `nixos-rebuild build-vm`. This option may
become the default value in the future.
====

[NOTE]
====
By default, Home Manager uses a private `pkgs` instance that is
configured via the `home-manager.users.<name>.nixpkgs` options. To
instead use the global `pkgs` that is configured via the system level
`nixpkgs` options, set

[source,nix]
home-manager.useGlobalPkgs = true;

This saves an extra Nixpkgs evaluation, adds consistency, and removes
the dependency on `NIX_PATH`, which is otherwise used for importing
Nixpkgs.
====

[NOTE]
====
Home Manager will pass `osConfig` as a module argument to any modules
you create. This contains the system's NixOS configuration.

[source,nix]
{ lib, pkgs, osConfig, ... }:
====

Once installed you can see <<ch-usage>> for a more detailed
description of Home Manager and how to use it.

[[sec-install-nix-darwin-module]]
=== nix-darwin module

Home Manager provides a module that allows you to prepare user
environments directly from the {nix-darwin}[nix-darwin] configuration
file, which often is more convenient than using the `home-manager`
tool.

To make the NixOS module available for use you must `import` it into
your system configuration. This is most conveniently done by adding a
Home Manager channel. For example, if you are following Nixpkgs master
or an unstable channel, you can run

[source,console]
----
$ nix-channel --add https://github.com/nix-community/home-manager/archive/master.tar.gz home-manager
$ nix-channel --update
----

and if you follow a Nixpkgs version 23.05 channel, you can run

[source,console]
----
$ nix-channel --add https://github.com/nix-community/home-manager/archive/release-23.05.tar.gz home-manager
$ nix-channel --update
----

It is then possible to add

[source,nix]
imports = [ <home-manager/nix-darwin> ];

to your nix-darwin `configuration.nix` file, which will introduce a
new NixOS option called `home-manager` whose type is an attribute set
that maps user names to Home Manager configurations.

For example, a nix-darwin configuration may include the lines

[source,nix]
----
users.users.eve = {
  name = "eve";
  home = "/Users/eve";
}
home-manager.users.eve = { pkgs, ... }: {
  home.packages = [ pkgs.atool pkgs.httpie ];
  programs.bash.enable = true;

  # The state version is required and should stay at the version you
  # originally installed.
  home.stateVersion = "23.05";
};
----

and after a `darwin-rebuild switch` the user eve's environment
should include a basic Bash configuration and the packages atool and
httpie.

If you do not plan on having Home Manager manage your shell
configuration then you must add either

[source,bash]
----
. "$HOME/.nix-profile/etc/profile.d/hm-session-vars.sh"
----

or

[source,bash]
----
. "/etc/profiles/per-user/$USER/etc/profile.d/hm-session-vars.sh"
----

to your shell configuration, depending on whether
<<nix-darwin-opt-home-manager.useUserPackages>> is enabled. This file
can be sourced directly by POSIX.2-like shells such as {bash}[Bash] or
{zsh}[Z shell]. {fish}[Fish] users can use utilities such as
{plugin-foreign-env}[foreign-env] or {babelfish}[babelfish].

[NOTE]
====
By default user packages will not be ignored in favor of
`environment.systemPackages`, but they will be installed to
`/etc/profiles/per-user/$USERNAME` if

[source,nix]
home-manager.useUserPackages = true;

is added to the nix-darwin configuration. This option may become the
default value in the future.
====

[NOTE]
====
By default, Home Manager uses a private `pkgs` instance that is
configured via the `home-manager.users.<name>.nixpkgs` options. To
instead use the global `pkgs` that is configured via the system level
`nixpkgs` options, set

[source,nix]
home-manager.useGlobalPkgs = true;

This saves an extra Nixpkgs evaluation, adds consistency, and removes
the dependency on `NIX_PATH`, which is otherwise used for importing
Nixpkgs.
====

[NOTE]
====
Home Manager will pass `osConfig` as a module argument to any modules
you create. This contains the system's nix-darwin configuration.

[source,nix]
{ lib, pkgs, osConfig, ... }:
====

Once installed you can see <<ch-usage>> for a more detailed
description of Home Manager and how to use it.
