Regular Expressions - match entire line contents

Question

I want to use regular expressions to search for a line consisting of one single word. Say the word was apple, and I am searching:

apple
banana
apple pear banana
apple banana
pear apple
pear

I only want it to match "apple". I do not want to match apple just at the beginning of the line, but when the line is equal to "apple".

Edit: for those asking why I'm using regular expressions, I need to check for the word case-insensitively, thus I'm using (?i)apple

Edit2: I'm modifying the title to reflect that this can be used not just for a specific word, but anytime we are looking for the entire contents of a line, rather than just matching lines that contain the expression

I'm trying to achieve what I asked in the question - to match a single word line only. If I do '(?i)apple' it will match all lines that contain "apple" — Joel M., Aug 31 '17 at 19:14
I've discovered a solution - I'm going to answer my own question since I haven't been able to find another answer. — Joel M., Aug 31 '17 at 19:16
Not a duplicate of that - the solution to that question will match all lines with words after "apple". — Joel M., Aug 31 '17 at 19:19
And I don't understand the downvotes - is the question not clear? — Joel M., Aug 31 '17 at 19:19
Does this answer your question? [How to make grep only match if the entire line matches?](https://stackoverflow.com/questions/4709912/how-to-make-grep-only-match-if-the-entire-line-matches) — tripleee, Feb 20 '20 at 13:53

Jan · Answer 1 · 2017-08-31T19:18:09.457

2

Use anchors:

^apple$

Or compare them via string functions as there do not seem to be changing parts which would make regular expression kind of a must.

edited Aug 31 '17 at 19:18

answered Aug 31 '17 at 19:16

Jan

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Thanks - that's what I just found. – Joel M. Aug 31 '17 at 19:17
I need the case insensitivity of regex, otherwise I would compare strings – Joel M. Aug 31 '17 at 19:29
@JoelM.: This might be a reason for the downvotes: you did not mention that you want it in the first place. – Jan Aug 31 '17 at 19:34

score 0 · Accepted Answer · answered Aug 31 '17 at 19:17

0

I found the solution after more experimentation - the answer is to search for the word at both the beginning (^) and end ($) of the line:

'^apple$'

answered Aug 31 '17 at 19:17

Joel M.

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A much better solution is to string compare it `== "apple"` Otherwise, for multi-line string, the anchors only match the beginning and end of string. For that you'd need `(?m)^apple$` which would find it on a line by itself. But, it still doesn't tell you much about it. – Aug 31 '17 at 19:38

Regular Expressions - match entire line contents

2 Answers2