2020-07-23 00:17:48 +03:00
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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
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convenient to manually download the latest set of Nix expressions for
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those packages and upgrade using `nix-env`. Fortunately, there’s a
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better way: *Nix channels*.
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A Nix channel is just a URL that points to a place that contains a set
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of Nix expressions and a manifest. Using the command
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2020-07-24 16:46:16 +03:00
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[`nix-channel`](../command-ref/nix-channel.md) you can automatically
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stay up to date with whatever is available at that URL.
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2020-07-23 00:17:48 +03:00
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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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You can “subscribe” to a channel using `nix-channel --add`, e.g.,
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2020-07-31 16:43:25 +03:00
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```console
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$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
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```
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2020-07-23 00:17:48 +03:00
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subscribes you to a channel that always contains that latest version of
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the Nix Packages collection. (Subscribing really just means that the URL
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is added to the file `~/.nix-channels`, where it is read by subsequent
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calls to `nix-channel
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--update`.) You can “unsubscribe” using `nix-channel
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--remove`:
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2020-07-31 16:43:25 +03:00
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```console
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$ nix-channel --remove nixpkgs
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```
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2020-07-23 00:17:48 +03:00
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To obtain the latest Nix expressions available in a channel, do
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2020-07-31 16:43:25 +03:00
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```console
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$ nix-channel --update
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```
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2020-07-23 00:17:48 +03:00
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This downloads and unpacks the Nix expressions in every channel
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(downloaded from `url/nixexprs.tar.bz2`). It also makes the union of
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each channel’s Nix expressions available by default to `nix-env`
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operations (via the symlink `~/.nix-defexpr/channels`). Consequently,
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you can then say
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2020-07-31 16:43:25 +03:00
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```console
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$ nix-env -u
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```
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2020-07-23 00:17:48 +03:00
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to upgrade all packages in your profile to the latest versions available
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in the subscribed channels.
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