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# Installing a Binary Distribution
The easiest way to install Nix is to run the following command:
```console
$ sh <(curl -L https://nixos.org/nix/install)
```
This will run the installer interactively (causing it to explain what
it is doing more explicitly), and perform the default "type" of install
for your platform:
- single-user on Linux
- multi-user on macOS
> **Notes on read-only filesystem root in macOS 10.15 Catalina +**
>
> - It took some time to support this cleanly. You may see posts,
> examples, and tutorials using obsolete workarounds.
> - Supporting it cleanly made macOS installs too complex to qualify
> as single-user, so this type is no longer supported on macOS.
We recommend the multi-user install if it supports your platform and
you can authenticate with `sudo`.
# Single User Installation
To explicitly select a single-user installation on your system:
```console
$ sh <(curl -L https://nixos.org/nix/install) --no-daemon
```
This will perform a single-user installation of Nix, meaning that `/nix`
is owned by the invoking user. You should run this under your usual user
account, *not* as root. The script will invoke `sudo` to create `/nix`
if it doesn’t already exist. If you don’t have `sudo`, you should
manually create `/nix` first as root, e.g.:
```console
$ mkdir /nix
$ chown alice /nix
```
The install script will modify the first writable file from amongst
`.bash_profile`, `.bash_login` and `.profile` to source
`~/.nix-profile/etc/profile.d/nix.sh`. You can set the
`NIX_INSTALLER_NO_MODIFY_PROFILE` environment variable before executing
the install script to disable this behaviour.
You can uninstall Nix simply by running:
```console
$ rm -rf /nix
```
# Multi User Installation
The multi-user Nix installation creates system users, and a system
service for the Nix daemon.
**Supported Systems**
- Linux running systemd, with SELinux disabled
- macOS
You can instruct the installer to perform a multi-user installation on
your system:
```console
$ sh <(curl -L https://nixos.org/nix/install) --daemon
```
The multi-user installation of Nix will create build users between the
user IDs 30001 and 30032, and a group with the group ID 30000. You
should run this under your usual user account, *not* as root. The script
will invoke `sudo` as needed.
> **Note**
>
> If you need Nix to use a different group ID or user ID set, you will
> have to download the tarball manually and [edit the install
> script](#installing-from-a-binary-tarball).
The installer will modify `/etc/bashrc`, and `/etc/zshrc` if they exist.
The installer will first back up these files with a `.backup-before-nix`
extension. The installer will also create `/etc/profile.d/nix.sh`.
You can uninstall Nix with the following commands:
```console
sudo rm -rf /etc/profile/nix.sh /etc/nix /nix ~root/.nix-profile ~root/.nix-defexpr ~root/.nix-channels ~/.nix-profile ~/.nix-defexpr ~/.nix-channels
# If you are on Linux with systemd, you will need to run:
sudo systemctl stop nix-daemon.socket
sudo systemctl stop nix-daemon.service
sudo systemctl disable nix-daemon.socket
sudo systemctl disable nix-daemon.service
sudo systemctl daemon-reload
# If you are on macOS, you will need to run:
sudo launchctl unload /Library/LaunchDaemons/org.nixos.nix-daemon.plist
sudo rm /Library/LaunchDaemons/org.nixos.nix-daemon.plist
```
There may also be references to Nix in `/etc/profile`, `/etc/bashrc`,
and `/etc/zshrc` which you may remove.
# macOS Installation <a name="sect-macos-installation-change-store-prefix"></a><a name="sect-macos-installation-encrypted-volume"></a><a name="sect-macos-installation-symlink"></a><a name="sect-macos-installation-recommended-notes"></a>
<!-- Note: anchors above to catch permalinks to old explanations -->
We believe we have ironed out how to cleanly support the read-only root
on modern macOS. New installs will do this automatically, and you can
also re-run a new installer to convert your existing setup.
This section previously detailed the situation, options, and trade-offs,
but it now only outlines what the installer does. You don't need to know
this to run the installer, but it may help if you run into trouble:
- create a new APFS volume for your Nix store
- update `/etc/synthetic.conf` to direct macOS to create a "synthetic"
empty root directory to mount your volume
- specify mount options for the volume in `/etc/fstab`
- `rw`: read-write
- `noauto`: prevent the system from auto-mounting the volume (so the
LaunchDaemon mentioned below can control mounting it, and to avoid
masking problems with that mounting service).
- `nobrowse`: prevent the Nix Store volume from showing up on your
desktop; also keeps Spotlight from spending resources to index
this volume
<!-- TODO:
- `suid`: honor setuid? surely not? ...
- `owners`: honor file ownership on the volume
For now I'll avoid pretending to understand suid/owners more
than I do. There've been some vague reports of file-ownership
and permission issues, particularly in cloud/VM/headless setups.
My pet theory is that this has something to do with these setups
not having a token that gets delegated to initial/admin accounts
on macOS. See scripts/create-darwin-volume.sh for a little more.
In any case, by Dec 4 2021, it _seems_ like some combination of
suid, owners, and calling diskutil enableOwnership have stopped
new reports from coming in. But I hesitate to celebrate because we
haven't really named and catalogued the behavior, understood what
we're fixing, and validated that all 3 components are essential.
-->
- if you have FileVault enabled
- generate an encryption password
- put it in your system Keychain
- use it to encrypt the volume
- create a system LaunchDaemon to mount this volume early enough in the
boot process to avoid problems loading or restoring any programs that
need access to your Nix store
# Installing a pinned Nix version from a URL
NixOS.org hosts version-specific installation URLs for all Nix versions
since 1.11.16, at `https://releases.nixos.org/nix/nix-version/install`.
These install scripts can be used the same as the main NixOS.org
installation script:
```console
$ sh <(curl -L https://nixos.org/nix/install)
```
In the same directory of the install script are sha256 sums, and gpg
signature files.
# Installing from a binary tarball
You can also download a binary tarball that contains Nix and all its
dependencies. (This is what the install script at
<https://nixos.org/nix/install> does automatically.) You should unpack
it somewhere (e.g. in `/tmp`), and then run the script named `install`
inside the binary tarball:
```console
$ cd /tmp
$ tar xfj nix-1.8-x86_64-darwin.tar.bz2
$ cd nix-1.8-x86_64-darwin
$ ./install
```
If you need to edit the multi-user installation script to use different
group ID or a different user ID range, modify the variables set in the
file named `install-multi-user`.
|
