Usage of need

English as a Second Language English Vocabulary, Grammar and Idioms
1

Is the following sentence correct?

  1. The file need not change.

Please help.

2

Yes.

3

But file is singular, isn’t it? Is it still OK?

4

Yes, it’s OK.

“Need” is not a full-verb in your example but is a marginal modal, and therefore does not take “s”.

Imagine:

*you musts do it