40 lines
1.5 KiB
Markdown
40 lines
1.5 KiB
Markdown
R"(
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**Store URL format**: `local`, *root*
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This store type accesses a Nix store in the local filesystem directly
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(i.e. not via the Nix daemon). *root* is an absolute path that is
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prefixed to other directories such as the Nix store directory. The
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store pseudo-URL `local` denotes a store that uses `/` as its root
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directory.
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A store that uses a *root* other than `/` is called a *chroot
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store*. With such stores, the store directory is "logically" still
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`/nix/store`, so programs stored in them can only be built and
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executed by `chroot`-ing into *root*. Chroot stores only support
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building and running on Linux when [`mount namespaces`](https://man7.org/linux/man-pages/man7/mount_namespaces.7.html) and [`user namespaces`](https://man7.org/linux/man-pages/man7/user_namespaces.7.html) are
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enabled.
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For example, the following uses `/tmp/root` as the chroot environment
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to build or download `nixpkgs#hello` and then execute it:
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```console
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# nix run --store /tmp/root nixpkgs#hello
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Hello, world!
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```
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Here, the "physical" store location is `/tmp/root/nix/store`, and
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Nix's store metadata is in `/tmp/root/nix/var/nix/db`.
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It is also possible, but not recommended, to change the "logical"
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location of the Nix store from its default of `/nix/store`. This makes
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it impossible to use default substituters such as
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`https://cache.nixos.org/`, and thus you may have to build everything
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locally. Here is an example:
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```console
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# nix build --store 'local?store=/tmp/my-nix/store&state=/tmp/my-nix/state&log=/tmp/my-nix/log' nixpkgs#hello
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```
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)"
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