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I would like to match lines that have the phrase a test but not start with >. So I want to match

This is a test
a test this is

but not

> This is a test

I am not sure how to do this without lookahead in emacs.

As a first try I tried^[^>].*a test. However, for some reason, this matches > This is a test when there's a newline before it which I don't understand since the first character in a line should not be >.

What is the correct regular expression for this case? And why is my regular expression matching lines starting with >.

emacs screenshot

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2 Answers 2

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The point is that the construct [^>] matches even a newline as stated in https://www.emacswiki.org/emacs/RegularExpression. Indeed such regex matches even the line above. So replacing it with [^>\n] solves the problem.

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Your problem must be something else; that regex looks fine to me. In fact, I used M-x regexp-builder to verify that it does work as expected.

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  • I just tried it with regexp-builder with emacs -Q and I am still getting > This is a test matched (I am adding an image to show this in my post). However, I now understand that the problem seems to be that if there is an empty line before > This is a test then I get the incorrect match (I edited my post to reflect this). Any idea why this is and how to fix it?
    – Tohiko
    Commented Apr 26, 2020 at 9:01

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