mirror of
https://github.com/NixOS/nix.git
synced 2025-12-04 08:00:59 +01:00
Merge branch 'master' into overlayfs-store
This commit is contained in:
Ben Radford
commit
21b9e15d25
21 changed files with 366 additions and 246 deletions
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@ -281,7 +281,7 @@ const redirects = {
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"chap-introduction": "introduction.html",
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"ch-basic-package-mgmt": "package-management/basic-package-mgmt.html",
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"ssec-binary-cache-substituter": "package-management/binary-cache-substituter.html",
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"sec-channels": "package-management/channels.html",
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"sec-channels": "command-ref/nix-channel.html",
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"ssec-copy-closure": "package-management/copy-closure.html",
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"sec-garbage-collection": "package-management/garbage-collection.html",
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"ssec-gc-roots": "package-management/garbage-collector-roots.html",
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@ -21,7 +21,6 @@
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- [Profiles](package-management/profiles.md)
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- [Garbage Collection](package-management/garbage-collection.md)
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- [Garbage Collector Roots](package-management/garbage-collector-roots.md)
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- [Channels](package-management/channels.md)
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- [Sharing Packages Between Machines](package-management/sharing-packages.md)
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- [Serving a Nix store via HTTP](package-management/binary-cache-substituter.md)
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- [Copying Closures via SSH](package-management/copy-closure.md)
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@ -8,36 +8,46 @@
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# Description
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A Nix channel is a mechanism that allows you to automatically stay
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up-to-date with a set of pre-built Nix expressions. A Nix channel is
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just a URL that points to a place containing a set of Nix expressions.
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Channels are a mechanism for referencing remote Nix expressions and conveniently retrieving their latest version.
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To see the list of official NixOS channels, visit
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<https://nixos.org/channels>.
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The moving parts of channels are:
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- The official channels listed at <https://nixos.org/channels>
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- The user-specific list of [subscribed channels](#subscribed-channels)
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- The [downloaded channel contents](#channels)
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- The [Nix expression search path](@docroot@/command-ref/conf-file.md#conf-nix-path), set with the [`-I` option](#opt-i) or the [`NIX_PATH` environment variable](#env-NIX_PATH)
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> **Note**
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>
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> The state of a subscribed channel is external to the Nix expressions relying on it.
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> This may limit reproducibility.
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>
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> Dependencies on other Nix expressions can be declared explicitly with:
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> - [`fetchurl`](@docroot@/language/builtins.md#builtins-fetchurl), [`fetchTarball`](@docroot@/language/builtins.md#builtins-fetchTarball), or [`fetchGit`](@docroot@/language/builtins.md#builtins-fetchGit) in Nix expressions
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> - the [`-I` option](@docroot@/command-ref/opt-common.md#opt-I) in command line invocations
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This command has the following operations:
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- `--add` *url* \[*name*\]\
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Adds a channel named *name* with URL *url* to the list of subscribed
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channels. If *name* is omitted, it defaults to the last component of
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*url*, with the suffixes `-stable` or `-unstable` removed.
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Add a channel *name* located at *url* to the list of subscribed channels.
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If *name* is omitted, default to the last component of *url*, with the suffixes `-stable` or `-unstable` removed.
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> **Note**
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>
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> `--add` does not automatically perform an update.
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> Use `--update` explicitly.
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A channel URL must point to a directory containing a file `nixexprs.tar.gz`.
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At the top level, that tarball must contain a single directory with a `default.nix` file that serves as the channel’s entry point.
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- `--remove` *name*\
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Removes the channel named *name* from the list of subscribed
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channels.
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Remove the channel *name* from the list of subscribed channels.
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- `--list`\
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Prints the names and URLs of all subscribed channels on standard
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output.
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Print the names and URLs of all subscribed channels on standard output.
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- `--update` \[*names*…\]\
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Downloads the Nix expressions of all subscribed channels (or only
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those included in *names* if specified) and makes them the default
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for `nix-env` operations (by symlinking them from the directory
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`~/.nix-defexpr`).
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Download the Nix expressions of subscribed channels and create a new generation.
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Update all channels if none is specified, and only those included in *names* otherwise.
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- `--list-generations`\
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Prints a list of all the current existing generations for the
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@ -49,13 +59,8 @@ This command has the following operations:
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```
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- `--rollback` \[*generation*\]\
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Reverts the previous call to `nix-channel
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--update`. Optionally, you can specify a specific channel generation
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number to restore.
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Note that `--add` does not automatically perform an update.
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The list of subscribed channels is stored in `~/.nix-channels`.
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Revert channels to the state before the last call to `nix-channel --update`.
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Optionally, you can specify a specific channel *generation* number to restore.
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{{#include ./opt-common.md}}
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@ -69,23 +74,33 @@ The list of subscribed channels is stored in `~/.nix-channels`.
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# Examples
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To subscribe to the Nixpkgs channel and install the GNU Hello package:
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Subscribe to the Nixpkgs channel and run `hello` from the GNU Hello package:
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```console
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$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
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$ nix-channel --list
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nixpkgs https://nixos.org/channels/nixpkgs
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$ nix-channel --update
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$ nix-env --install --attr nixpkgs.hello
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$ nix-shell -p hello --run hello
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hello
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```
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You can revert channel updates using `--rollback`:
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Revert channel updates using `--rollback`:
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```console
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$ nix-instantiate --eval --expr '(import <nixpkgs> {}).lib.version'
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"14.04.527.0e935f1"
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$ nix-instantiate --eval '<nixpkgs>' --attr lib.version
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"22.11pre296212.530a53dcbc9"
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$ nix-channel --rollback
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switching from generation 483 to 482
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$ nix-instantiate --eval --expr '(import <nixpkgs> {}).lib.version'
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"14.04.526.dbadfad"
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$ nix-instantiate --eval '<nixpkgs>' --attr lib.version
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"22.11pre281526.d0419badfad"
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```
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Remove a channel:
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```console
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$ nix-channel --remove nixpkgs
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$ nix-channel --list
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```
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@ -110,41 +110,72 @@ You can also build Nix for one of the [supported platforms](#platforms).
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## Platforms
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As specified in [`flake.nix`], Nix can be built for various platforms:
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- `aarch64-linux`
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- `i686-linux`
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- `x86_64-darwin`
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- `x86_64-linux`
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Nix can be built for various platforms, as specified in [`flake.nix`]:
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[`flake.nix`]: https://github.com/nixos/nix/blob/master/flake.nix
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- `x86_64-linux`
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- `x86_64-darwin`
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- `i686-linux`
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- `aarch64-linux`
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- `aarch64-darwin`
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- `armv6l-linux`
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- `armv7l-linux`
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In order to build Nix for a different platform than the one you're currently
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on, you need to have some way for your system Nix to build code for that
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platform. Common solutions include [remote builders] and [binfmt emulation]
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on, you need a way for your current Nix installation to build code for that
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platform. Common solutions include [remote builders] and [binary format emulation]
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(only supported on NixOS).
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[remote builders]: ../advanced-topics/distributed-builds.md
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[binfmt emulation]: https://nixos.org/manual/nixos/stable/options.html#opt-boot.binfmt.emulatedSystems
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These solutions let Nix perform builds as if you're on the native platform, so
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executing the build is as simple as
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```console
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$ nix build .#packages.aarch64-linux.default
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```
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for flake-enabled Nix, or
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Given such a setup, executing the build only requires selecting the respective attribute.
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For example, to compile for `aarch64-linux`:
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```console
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$ nix-build --attr packages.aarch64-linux.default
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```
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for classic Nix.
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or for Nix with the [`flakes`] and [`nix-command`] experimental features enabled:
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You can use any of the other supported platforms in place of `aarch64-linux`.
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```console
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$ nix build .#packages.aarch64-linux.default
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```
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Cross-compiled builds are available for ARMv6 and ARMv7, and Nix on unsupported platforms can be bootstrapped by adding more `crossSystems` in `flake.nix`.
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Cross-compiled builds are available for ARMv6 (`armv6l-linux`) and ARMv7 (`armv7l-linux`).
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Add more [system types](#system-type) to `crossSystems` in `flake.nix` to bootstrap Nix on unsupported platforms.
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## System type
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Nix uses a string with he following format to identify the *system type* or *platform* it runs on:
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```
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<cpu>-<os>[-<abi>]
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```
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It is set when Nix is compiled for the given system, and based on the output of [`config.guess`](https://github.com/nixos/nix/blob/master/config/config.guess) ([upstream](https://git.savannah.gnu.org/cgit/config.git/tree/config.guess)):
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```
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<cpu>-<vendor>-<os>[<version>][-<abi>]
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```
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When Nix is built such that `./configure` is passed any of the `--host`, `--build`, `--target` options, the value is based on the output of [`config.sub`](https://github.com/nixos/nix/blob/master/config/config.sub) ([upstream](https://git.savannah.gnu.org/cgit/config.git/tree/config.sub)):
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```
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<cpu>-<vendor>[-<kernel>]-<os>
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```
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For historic reasons and backward-compatibility, some CPU and OS identifiers are translated from the GNU Autotools naming convention in [`configure.ac`](https://github.com/nixos/nix/blob/master/config/config.sub) as follows:
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| `config.guess` | Nix |
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|----------------------------|---------------------|
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| `amd64` | `x86_64` |
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| `i*86` | `i686` |
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| `arm6` | `arm6l` |
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| `arm7` | `arm7l` |
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| `linux-gnu*` | `linux` |
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| `linux-musl*` | `linux` |
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## Compilation environments
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@ -92,10 +92,10 @@ In this fragment from `all-packages.nix`,
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```nix
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graphviz = (import ../tools/graphics/graphviz) {
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inherit fetchurl stdenv libpng libjpeg expat x11 yacc;
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inherit (xlibs) libXaw;
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inherit (xorg) libXaw;
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};
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xlibs = {
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xorg = {
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libX11 = ...;
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libXaw = ...;
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...
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@ -109,7 +109,7 @@ libjpg = ...;
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the set used in the function call to the function defined in
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`../tools/graphics/graphviz` inherits a number of variables from the
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surrounding scope (`fetchurl` ... `yacc`), but also inherits `libXaw`
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(the X Athena Widgets) from the `xlibs` (X11 client-side libraries) set.
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(the X Athena Widgets) from the `xorg` set.
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Summarizing the fragment
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@ -208,30 +208,41 @@ three kinds of patterns:
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```nix
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{ x, y, z, ... } @ args: z + y + x + args.a
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```
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Here `args` is bound to the entire argument, which is further
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matched against the pattern `{ x, y, z,
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... }`. `@`-pattern makes mainly sense with an ellipsis(`...`) as
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Here `args` is bound to the argument *as passed*, which is further
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matched against the pattern `{ x, y, z, ... }`.
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The `@`-pattern makes mainly sense with an ellipsis(`...`) as
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you can access attribute names as `a`, using `args.a`, which was
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given as an additional attribute to the function.
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> **Warning**
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>
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> The `args@` expression is bound to the argument passed to the
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> function which means that attributes with defaults that aren't
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> explicitly specified in the function call won't cause an
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> evaluation error, but won't exist in `args`.
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>
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>
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> `args@` binds the name `args` to the attribute set that is passed to the function.
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> In particular, `args` does *not* include any default values specified with `?` in the function's set pattern.
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>
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> For instance
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>
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>
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> ```nix
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> let
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> function = args@{ a ? 23, ... }: args;
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> f = args@{ a ? 23, ... }: [ a args ];
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> in
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> function {}
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> ````
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>
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||||
> will evaluate to an empty attribute set.
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> f {}
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> ```
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>
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||||
> is equivalent to
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>
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> ```nix
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> let
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> f = args @ { ... }: [ (args.a or 23) args ];
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> in
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> f {}
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> ```
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>
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> and both expressions will evaluate to:
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>
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> ```nix
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> [ 23 {} ]
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> ```
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Note that functions do not have names. If you want to give them a name,
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you can bind them to an attribute, e.g.,
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|
|
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|
@ -25,7 +25,7 @@ or completely new ones.)
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|||
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You can manually download the latest version of Nixpkgs from
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<https://github.com/NixOS/nixpkgs>. However, it’s much more
|
||||
convenient to use the Nixpkgs [*channel*](channels.md), since it makes
|
||||
convenient to use the Nixpkgs [*channel*](../command-ref/nix-channel.md), since it makes
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it easy to stay up to date with new versions of Nixpkgs. Nixpkgs is
|
||||
automatically added to your list of “subscribed” channels when you
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||||
install Nix. If this is not the case for some reason, you can add it
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|
|
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|||
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|
@ -1,50 +0,0 @@
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|||
# Channels
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||||
|
||||
If you want to stay up to date with a set of packages, it’s not very
|
||||
convenient to manually download the latest set of Nix expressions for
|
||||
those packages and upgrade using `nix-env`. Fortunately, there’s a
|
||||
better way: *Nix channels*.
|
||||
|
||||
A Nix channel is just a URL that points to a place that contains a set
|
||||
of Nix expressions and a manifest. Using the command
|
||||
[`nix-channel`](../command-ref/nix-channel.md) you can automatically
|
||||
stay up to date with whatever is available at that URL.
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||||
|
||||
To see the list of official NixOS channels, visit
|
||||
<https://nixos.org/channels>.
|
||||
|
||||
You can “subscribe” to a channel using `nix-channel --add`, e.g.,
|
||||
|
||||
```console
|
||||
$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
|
||||
```
|
||||
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||||
subscribes you to a channel that always contains that latest version of
|
||||
the Nix Packages collection. (Subscribing really just means that the URL
|
||||
is added to the file `~/.nix-channels`, where it is read by subsequent
|
||||
calls to `nix-channel
|
||||
--update`.) You can “unsubscribe” using `nix-channel
|
||||
--remove`:
|
||||
|
||||
```console
|
||||
$ nix-channel --remove nixpkgs
|
||||
```
|
||||
|
||||
To obtain the latest Nix expressions available in a channel, do
|
||||
|
||||
```console
|
||||
$ nix-channel --update
|
||||
```
|
||||
|
||||
This downloads and unpacks the Nix expressions in every channel
|
||||
(downloaded from `url/nixexprs.tar.bz2`). It also makes the union of
|
||||
each channel’s Nix expressions available by default to `nix-env`
|
||||
operations (via the symlink `~/.nix-defexpr/channels`). Consequently,
|
||||
you can then say
|
||||
|
||||
```console
|
||||
$ nix-env --upgrade
|
||||
```
|
||||
|
||||
to upgrade all packages in your profile to the latest versions available
|
||||
in the subscribed channels.
|
||||
Loading…
Add table
Add a link
Reference in a new issue