How to install Unity 8 on 13.10

[mc4man]

How do I get rid of it? Sorry for all the questions I'm not that good with this kind of stuff.

While it wouldn't really matter if you remove the || may as well fix the mistake.

Open up /unity/unity8/build in a text editor.
scroll down to line 55, put your cursor to the immediate left of the first | and backspace till it is on a line right below "unity-lens-applications \"
Where on that line doesn't particularly matter, far left is ok, see screen (point is that there can't be an empty line between line # 53 & || exit 5
Then ./build -s will run