DocPad should exit when (1) used with sudo (2) when sudo is required

[balupton]

One of the most common issues that people run into with DocPad as well as other node modules is permission errors due to incorrectly configuration installations of node. If people are using DocPad with sudo then we should error and tell them no. If people are using DocPad and permissions aren't set correctly, we should also exit and tell them no.

Besides the usual permission errors, here are some other issues caused by sudo and incorrect permissions:

• Get it to work with proxies #488 (comment)
• docpad upgrade removed my NPM installation & docpad executable. #990

[balupton]

Anyone have any idea how to detect if sudo is being used?

[jrbart]

You can check for the SUDO_USER environment variable, but that can be tampered with.

But, if you check "getuid" and see that you are root, wouldn't you want to bail out no matter how you got there (setuid, sudo, root login...)? You might also compare real and effective uids and bail out if they are not the same, or if they are a system user.