A [recent-ish change](https://github.com/NixOS/nix/pull/6676) logs a warning when a potentially counterintuitive situation happens.
This now causes the multi-user installer to [emit a warning](https://github.com/NixOS/nixpkgs/issues/189043) when it's doing
the "seed the Nix database" step via a low-level `nix-store --load-db` invocation.
`nix-store` functionality implementations don't actually use profiles or channels or homedir as far as i can tell. So why are we
hitting this code at all?
Well, the current command approach for functionality here builds a [fat `nix` binary](https://github.com/NixOS/nix/blob/master/src/nix/local.mk#L23-L26) which has _all_ the functionality of
previous individual binaries (nix-env, nix-store, etc) bundled in, then [uses the invocation name](https://github.com/NixOS/nix/blob/master/src/nix/main.cc#L274-L277) to select the
set of commands to expose. `nix` itself has this behavior, even when just trying to parse the (sub)command and arguments:
```
dave @ davembp2
$ nix
error: no subcommand specified
Try 'nix --help' for more information.
dave @ davembp2
$ sudo nix
warning: $HOME ('/Users/dave') is not owned by you, falling back to the one defined in the 'passwd' file
error: no subcommand specified
Try 'nix --help' for more information.
dave @ davembp2
$ HOME=~root sudo nix
error: no subcommand specified
Try 'nix --help' for more information.
```
This behavior can also be seen pretty easily with an arbitrary `nix-store` invocation:
```
dave @ davembp2
$ nix-store --realize
dave @ davembp2
$ sudo nix-store --realize # what installer is doing now
warning: $HOME ('/Users/dave') is not owned by you, falling back to the one defined in the 'passwd' file
dave @ davembp2
$ sudo HOME=~root nix-store --realize # what this PR effectively does
dave @ davembp2
$
```
On Linux a user can go through all the way through the multi-user install
and find out at the end that they now have to manually configure their
init system to launch the nix daemon.
I suspect that for a significant number of users this is not
what they wanted. They might prefer a single-user install.
Now they have to manually uninstall nix before they can
go through the single-user install.
This introduces a confirmation dialog before the install
in that specific situation to make sure that they want to proceed.
See also: https://github.com/NixOS/nix/issues/4999#issuecomment-1064188080
This closes#4999 but rejecting it and closing that issue anyways
would also be valid.
The script is trying to find chown in a cross-platform-like
way, but there's some sort of deficiency in `command -p` in
the default macOS bash 3.2. It looks like it will just use
whatever PATH is already set, instead of the "default" path.
This attempts to hard-set a PATH via `getconf PATH`. It will
just set an empty PATH if that fails for some reason. A
properly-functioning `command -p` should not care what we
set the PATH to here one way or the other.
Hopefully fixes#5768.
We had a macOS user present in Matrix with some confusion because the
lack of a clear task statement here made them think the error meant
that a problem had occurred during the preceding task in a macOS
install: "Fixing any leftover Nix volume state"
This reverts commit 909d8cb293.
This messes up PATH priority since /etc/profile gets sourced AFTER
/etc/zshenv and it sets the system paths so
$HOME/.nix-profile/bin:/nix/var/nix/profiles/default/bin is behind
/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin. See discussion in
https://github.com/NixOS/nix/issues/4169.
Env vars for ZSH were moved from /etc/zshrc to /etc/zshenv in #3608
to address an issue with zshrc getting clobbered by OS updates, but
/etc/zshenv doesn't exist by default--so *nothing* would get set up
for zsh users unless they already happened to have /etc/zshenv.
Creating these files if they don't exist. Also cut separate creation
of profile.d/nix.sh, which isn't needed now.
Some of the changes in #3788 to support non-systemd Nix installs
don't appear to be aware that the darwin installer exists, which
resulted in some skipped steps and inappropriate instructions.
The install-multi-user script uses blue, green, and red colors, as
well as bold and underline, to add helpful formatting that helps
structure its rather voluminous output.
Unfortunately, the terminal escape sequences it uses are not quite
well-formed. The relevant information is all there, just obscured
by some extra noise, a leading parameter `38`. Empirically, the
result is:
* On macOS, in both Terminal.app and iTerm2, the spurious `38` is
ignored, the rest of the escape sequence is applied, and the colors
show up as intended.
* On Linux, in at least gnome-terminal and xterm, the spurious `38`
and the next parameter after it are ignored, and what's left is
applied. So in the sequence `38;4;32`, the 4 (underline) is
ignored but the 32 (green) takes effect; in a more typical sequence
like `38;34`, the 34 (blue) is ignored and nothing happens.
These codes are all unchanged since this script's origins as a
Darwin-only script -- so the fact that they work fine in common macOS
terminals goes some way to explain how the bug arose.
Happily, we can make the colors work as intended by just deleting the
extra `38;`. Tested in all four terminals mentioned above; the new
codes work correctly on all of them, and on the two macOS terminals
they work exactly the same as before.
---
In a bit more technical detail -- perhaps more than anyone, me
included, ever wanted to know, but now that I've gone and learned it
I'll write it down anyway :) -- here's what's happening in these codes:
An ECMA-48 "control sequence" begins with `\033[` aka "CSI", contains
any number of parameters as semicolon-separated decimal numbers (plus
sometimes other wrinkles), and ends with a byte from 0x40..0x7e. In
our case, with `m` aka "SGR", "Select Graphic Rendition".
An SGR control sequence `\033[...m` sets colors, fonts, text styles,
etc. In particular a parameter `31` means red, `32` green, `34` blue,
`4` underline, and `0` means reset to normal. Those are all we use.
There is also a `38`. This is used for setting colors too... but it
needs arguments. `38;5;nn` is color nn from a 256-color palette, and
`38;2;rr;gg;bb` has the given RGB values.
There is no meaning defined for `38;1` or `38;34` etc. On seeing a
parameter `38` followed by an unrecognized argument for it, apparently
some implementations (as seen on macOS) discard only the `38` and
others (as seen on Linux) discard the argument too before resuming.
After installing Nix, I found that all the files and directories
initially copied into the store were writable, with mode 644 or 755:
drwxr-xr-x 9 root root 4096 Dec 31 1969 /nix/store/ddmmzn4ggz1f66lwxjy64n89864yj9w9-nix-2.3.3
The reason is that that's how they were in the unpacked tarball, and
the install-multi-user script used `rsync -p` without doing anything
else to affect the permissions.
The plain `install` script for a single-user install takes care to
do a `chmod -R a-w` on each store path copied. We could do the same
here with one more command; or we can pass `--chmod` to rsync, to
have it write the files with the desired modes in the first place.
Tested the new `rsync` command on both a Linux machine with a
reasonably-modern rsync (3.1.3) and a Mac with its default, ancient,
rsync 2.6.9, and it works as expected on both. Thankfully the latter
is just new enough to have `--chmod`, which dates to rsync 2.6.7.
In the multi-user install script, we originally made sure no previous
references to Nix existed. This prevented any previous installs from
contaminating the new install. However, some users need the ability to
repair their existing Nix installation without uninstalling all
references to Nix. This change allows users with existing Nix
installations to use the installer, while still outputing a warning
message on the dangers of this. As a result, the multi-user install
script work much more like the single-user install script has worked
in the past.
This is a requirement for macOS Catalina users now that
/Library/LaunchDaemons/org.nixos.nix-daemon.plisg is not managed by
the Nix store. If there is ever a change to the .plist, all users will
need to rerun this install script to get the new changes. Otherwise,
changes to the launch daemon will require manual interventions.
With macOS catalina, we can no longer modify the root system
volume (#2925). macOS provides a system configuration file in
synthetic.conf(5) to create empty root directories. This can be used
to mount /nix to a separate volume. As a result, this directory will
need to already exist prior to installation. Instead, check for
/nix/store and /nix/var for a live Nix installation.
