Improve explanation of NIX_PATH prefix syntax

The previous wording seemed to imply that the "channel:" syntax would resolve to
a github archive URL, which is not the case.
This commit is contained in:
Keshav Kini 2021-06-03 17:59:39 -07:00
parent bb06640971
commit f35f9af787

View file

@ -10,35 +10,39 @@ Most Nix commands interpret the following environment variables:
A colon-separated list of directories used to look up Nix
expressions enclosed in angle brackets (i.e., `<path>`). For
instance, the value
/home/eelco/Dev:/etc/nixos
will cause Nix to look for paths relative to `/home/eelco/Dev` and
`/etc/nixos`, in this order. It is also possible to match paths
against a prefix. For example, the value
nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos
will cause Nix to search for `<nixpkgs/path>` in
`/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`.
If a path in the Nix search path starts with `http://` or
`https://`, it is interpreted as the URL of a tarball that will be
downloaded and unpacked to a temporary location. The tarball must
consist of a single top-level directory. For example, setting
`NIX_PATH` to
nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-15.09.tar.gz
tells Nix to download the latest revision in the Nixpkgs/NixOS 15.09
channel.
A following shorthand can be used to refer to the official channels:
nixpkgs=channel:nixos-15.09
The search path can be extended using the `-I` option, which takes
precedence over `NIX_PATH`.
nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
tells Nix to download and use the current contents of the
`master` branch in the `nixpkgs` repository.
The URLs of the tarballs from the official nixos.org channels (see
[the manual for `nix-channel`](nix-channel.md)) can be abbreviated
as `channel:<channel-name>`. For instance, the following two
values of `NIX_PATH` are equivalent:
nixpkgs=channel:nixos-21.05
nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
The Nix search path can also be extended using the `-I` option to
many Nix commands, which takes precedence over `NIX_PATH`.
- `NIX_IGNORE_SYMLINK_STORE`\
Normally, the Nix store directory (typically `/nix/store`) is not
@ -50,7 +54,7 @@ Most Nix commands interpret the following environment variables:
builds are deployed to machines where `/nix/store` resolves
differently. If you are sure that youre not going to do that, you
can set `NIX_IGNORE_SYMLINK_STORE` to `1`.
Note that if youre symlinking the Nix store so that you can put it
on another file system than the root file system, on Linux youre
better off using `bind` mount points, e.g.,
@ -59,7 +63,7 @@ Most Nix commands interpret the following environment variables:
$ mkdir /nix
$ mount -o bind /mnt/otherdisk/nix /nix
```
Consult the mount 8 manual page for details.
- `NIX_STORE_DIR`\