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 - The downloaded channel contents -  The  Nix expression search
       path, set with the -I option or the NIX_PATH environment variable

              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,  fetchTarball,
              or fetchGit in Nix expressions - the -I option 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 channel’s 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:

       $ 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:

       $ 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:

       $ nix-channel --remove nixpkgs
       $ nix-channel --list

                                                                                                  nix-channel(1)