[Nix-dev] Upgrading NixOS with sudo results in some error

[Roger Qiu]

Hello,

When I try running:

``
sudo nixos-rebuild switch --upgrade
```

I get this message:

```
/run/current-system/sw/bin/nix-channel: unable to check 
`https://nixos.org/channels/nixos-14.04'
```

What does that mean? And how can I fix it?

It only happens when I use sudo with it. I cannot use the normal user 
because of permission problems, so I end up have to switch to root user 
and running it for it to succeed. But even as root, if I prefix the 
command with `sudo` it still fails with that problem.

Thanks,
Roger