nix-super/doc/manual/source/command-ref/nix-channel.md
John Ericson eb7d7780b1 Rename doc/manual{src -> source}
This is needed to avoid this
https://github.com/mesonbuild/meson/issues/13774 when we go back to
making our subproject directory `src`.
2024-10-14 11:21:24 -04:00

112 lines
3.4 KiB
Markdown
Raw Permalink Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

# Name
`nix-channel` - manage Nix channels
# Synopsis
`nix-channel` {`--add` url [*name*] | `--remove` *name* | `--list` | `--update` [*names…*] | `--list-generations` | `--rollback` [*generation*] }
# Description
Channels are a mechanism for referencing remote Nix expressions and conveniently retrieving their latest version.
The moving parts of channels are:
- The official channels listed at <https://nixos.org/channels>
- The user-specific list of [subscribed channels](#subscribed-channels)
- The [downloaded channel contents](#channels)
- 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)
> **Note**
>
> The state of a subscribed channel is external to the Nix expressions relying on it.
> This may limit reproducibility.
>
> Dependencies on other Nix expressions can be declared explicitly with:
> - [`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
> - the [`-I` option](@docroot@/command-ref/opt-common.md#opt-I) in command line invocations
This command has the following operations:
- `--add` *url* \[*name*\]
Add a channel *name* located at *url* to the list of subscribed channels.
If *name* is omitted, default to the last component of *url*, with the suffixes `-stable` or `-unstable` removed.
> **Note**
>
> `--add` does not automatically perform an update.
> Use `--update` explicitly.
A channel URL must point to a directory containing a file `nixexprs.tar.gz`.
At the top level, that tarball must contain a single directory with a `default.nix` file that serves as the channels entry point.
- `--remove` *name*
Remove the channel *name* from the list of subscribed channels.
- `--list`
Print the names and URLs of all subscribed channels on standard output.
- `--update` \[*names*…\]
Download the Nix expressions of subscribed channels and create a new generation.
Update all channels if none is specified, and only those included in *names* otherwise.
- `--list-generations`
Prints a list of all the current existing generations for the
channel profile.
Works the same way as
```
nix-env --profile /nix/var/nix/profiles/per-user/$USER/channels --list-generations
```
- `--rollback` \[*generation*\]
Revert channels to the state before the last call to `nix-channel --update`.
Optionally, you can specify a specific channel *generation* number to restore.
{{#include ./opt-common.md}}
{{#include ./env-common.md}}
# Files
`nix-channel` operates on the following files.
{{#include ./files/channels.md}}
# Examples
Subscribe to the Nixpkgs channel and run `hello` from the GNU Hello package:
```console
$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
$ nix-channel --list
nixpkgs https://nixos.org/channels/nixpkgs
$ nix-channel --update
$ nix-shell -p hello --run hello
hello
```
Revert channel updates using `--rollback`:
```console
$ nix-instantiate --eval '<nixpkgs>' --attr lib.version
"22.11pre296212.530a53dcbc9"
$ nix-channel --rollback
switching from generation 483 to 482
$ nix-instantiate --eval '<nixpkgs>' --attr lib.version
"22.11pre281526.d0419badfad"
```
Remove a channel:
```console
$ nix-channel --remove nixpkgs
$ nix-channel --list
```