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.
		
	
			
		
			
				
	
	
		
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			37 lines
		
	
	
	
		
			893 B
		
	
	
	
		
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| #! @shell@ -e
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| 
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| url=$1
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| 
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| if test -z "$url"; then
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|     echo "syntax: nix-prefetch-url URL" >&2
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|     exit 1
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| fi
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| 
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| # !!! race? should be relatively safe, `svn export' barfs if $tmpPath exists.
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| tmpPath1=@storedir@/nix-prefetch-url-$$
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| 
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| # Perform the checkout.
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| @curl@ --fail --location --max-redirs 20 "$url" > $tmpPath1
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| 
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| # Compute the hash.
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| hash=$(@bindir@/nix-hash --flat $tmpPath1)
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| echo "hash is $hash" >&2
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| 
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| # Rename it so that the fetchsvn builder can find it.
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| tmpPath2=@storedir@/nix-prefetch-url-$hash
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| test -e $tmpPath2 || mv $tmpPath1 $tmpPath2 # !!! race
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| 
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| # Create a Nix expression that does a fetchsvn.
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| storeExpr=$( \
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|   echo "(import @datadir@/nix/corepkgs/fetchurl) \
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|         {url = $url; md5 = \"$hash\"; system = \"@system@\";}" \
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|   | nix-instantiate -)
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| 
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| # Realise it.
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| finalPath=$(nix-store -qnB --force-realise $storeExpr)
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| 
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| echo "path is $finalPath" >&2
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| 
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| rm -rf $tmpPath2 || true
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| 
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| echo $hash
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