anchor.diff:    buildInputs = [
       libnih
       util-linux_lib
  +  ] ++ optionals (channel == "dev") [
  +    keyutils
  +    libscrypt
  +    libsodium
     ];
   
     preBuild = ''
  
positive.code:       "PREFIX=$out"
        "UDEVLIBDIR=$out/lib/udev"
      )
    '';
  
    preInstall = ''
      mkdir -p "$out/lib/udev/rules.d"
      mkdir -p "$out/bin"
      mkdir -p "$out/sbin"
      mkdir -p "$out/share/man/man8"
    '';
  
    meta = with stdenv.lib; {
  
negative.code:       sha256 = "496ae8691eb9c5a233bd99ed7984cbe129d702c322dc540143cd4012b24a4dad";
      };
      "dev" = {
        version = "2016-08-25";
        rev = "97de91cb580a2e31352860dfc0642579d21d3b7a";
        sha256 = "0f42bcd2f3226ad6e1bb0d3f8948a149467dcfa6e37d12c0421656159cb4d51c";
      };
    };
  
    inherit (stdenv.lib)
      optionals
      optionalString;
  
    inherit (sources.${channel})
      rev
  