* Channels. These allow you to stay current with an evolving set of

Nix expressions.

  To subscribe to a channel (needs to be done only once):

    nix-channel --add \
      http://catamaran.labs.cs.uu.nl/dist/nix/channels/nixpkgs-unstable

  This just adds the given URL to ~/.nix-channels (which can also be
  edited manually).

  To update from all channels:

    nix-channel --update

  This fetches the latest expressions and pulls cache manifests.  The
  default Nix expression (~/.nix-defexpr) is made to point to the
  conjunction of the expressions downloaded from all channels.

  So to update all installed derivations in the current user
  environment:

    nix-channel --update
    nix-env --upgrade '*'

  If you are really courageous, you can put this in a cronjob or
  something.

  You can subscribe to multiple channels.  It is not entirely clear
  what happens when there are name clashes between derivations from
  different channels.  From nix-env/main.cc it appears that the one
  with the lowest (highest?) hash will be used, which is pretty
  meaningless.

scripts/Makefile.am

@@ -1,6 +1,6 @@
 bin_SCRIPTS = nix-collect-garbage \
  nix-pull nix-push nix-prefetch-url \
- nix-install-package
+ nix-install-package nix-channel
 
 noinst_SCRIPTS = nix-profile.sh
 
@@ -20,4 +20,5 @@ include ../substitute.mk
 EXTRA_DIST = nix-collect-garbage.in \
  nix-pull.in nix-push.in nix-profile.sh.in \
  nix-prefetch-url.in nix-install-package.in \
+ nix-channel.in \
  prebuilts.conf readmanifest.pm.in