I recently got another email from a confused reader of vi(1) Tips: Essential vi/vim Editor Skills, 1st ed. I am quoting it and my reply hoping it will help those who are also confused.

Dear Sir,

Thinking to buy a good modern book on vi I looked at your book. I was startled to see an entirely new term, i.e. vi(1). Soon you introduce vi(I) that is a roman numeral inside the parentheses. It is hard for me to believe that vi(1) is the same as vi, but a series of glances through the book NEVER defines vi(1).

I may never find out what this (1) string is for but in any case

I can't recommend the book as long as this mystery hangs around it.

Sincerely yours,

(name withheld to protect the reader's privacy)

And my reply:

Dear Sir,

vi(1) is a reference to the Unix manual page for the vi editor, which you can display on the Unix command line using the following command:

$ man 1 vi

or

$ man vi

You don't need to type $, it is used to represent the Unix command-line prompt

As for vi(I) that is an artifact of the typeface we used to typeset the book. The numer 1 is represented by a shape that looks more like I and 1. We will fix it in the next edition.

Thank you for writing.

Kind Regards,

Jacek Artymiak