nixos-install - Man Page

nixos-install [{ --verbose | -v }] [-I path] [--root root] [--system path] [--flake flake-uri] [{--impure}] [--channel channel] [--no-channel-copy] [{ --no-root-password | --no-root-passwd }] [--no-bootloader] [{ --max-jobs | -j } number] [--cores number] [--option name value] [--show-trace] [--keep-going] [--help]

This command installs NixOS in the file system mounted on /mnt, based on the NixOS configuration specified in /mnt/etc/nixos/configuration.nix. It performs the following steps:

• It copies Nix and its dependencies to /mnt/nix/store.
• It runs Nix in /mnt to build the NixOS configuration specified in /mnt/etc/nixos/configuration.nix.
• It installs the current channel “nixos” in the target channel profile (unless --no-channel-copy is specified).
• It installs the GRUB boot loader on the device specified in the option boot.loader.grub.device (unless --no-bootloader is specified), and generates a GRUB configuration file that boots into the NixOS configuration just installed.
• It prompts you for a password for the root account (unless --no-root-password is specified).

This command is idempotent: if it is interrupted or fails due to a temporary problem (e.g. a network issue), you can safely re-run it.

This command accepts the following options:

--verbose / -v

Increases the level of verbosity of diagnostic messages printed on standard error. For each Nix operation, the information printed on standard output is well-defined; any diagnostic information is printed on standard error, never on standard output.

Please note that this option may be specified repeatedly.

--root

Defaults to /mnt. If this option is given, treat the directory root as the root of the NixOS installation.

--system

If this option is provided, nixos-install will install the specified closure rather than attempt to build one from /mnt/etc/nixos/configuration.nix.

The closure must be an appropriately configured NixOS system, with boot loader and partition configuration that fits the target host. Such a closure is typically obtained with a command such as nix-build -I nixos-config=./configuration.nix '<nixpkgs/nixos>' -A system --no-out-link

--flake flake-uri#name

Build the NixOS system from the specified flake. The flake must contain an output named nixosConfigurations.name.

--channel

If this option is provided, do not copy the current “nixos” channel to the target host. Instead, use the specified derivation.

-I

Add a path to the Nix expression search path. This option may be given multiple times. See the NIX_PATH environment variable for information on the semantics of the Nix search path. Paths added through -I take precedence over NIX_PATH.

--max-jobs,  -j

Sets the maximum number of build jobs that Nix will perform in parallel to the specified number. The default is 1. A higher value is useful on SMP systems or to exploit I/O latency.

--cores

Sets the value of the NIX_BUILD_CORES environment variable in the invocation of builders. Builders can use this variable at their discretion to control the maximum amount of parallelism. For instance, in Nixpkgs, if the derivation attribute enableParallelBuilding is set to true, the builder passes the -jN flag to GNU Make. The value 0 means that the builder should use all available CPU cores in the system.

--option name value

Set the Nix configuration option name to value.

--show-trace

Causes Nix to print out a stack trace in case of Nix expression evaluation errors.

--keep-going

Causes Nix to continue building derivations as far as possible in the face of failed builds.

--help

Synonym for man nixos-install.

A typical NixOS installation is done by creating and mounting a file system on /mnt, generating a NixOS configuration in /mnt/etc/nixos/configuration.nix, and running nixos-install. For instance, if we want to install NixOS on an ext4 file system created in /dev/sda1:

$ mkfs.ext4 /dev/sda1
$ mount /dev/sda1 /mnt
$ nixos-generate-config --root /mnt
$ # edit /mnt/etc/nixos/configuration.nix
$ nixos-install
$ reboot

Eelco Dolstra

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