Grep: How to grep for a string containing a colon

Question

I want to grep for a string which begins with a colon :, the contains 0 or more characters of anything, and then ends with the string mystring.

I tried this: grep -rI ':*mystring' . but this did not work.

From searching, I believe the reason this does not work is because it is matching "0 or more instances of the colon character : followed by mystring. (See an answer on this question)

That doesn't make much sense to me, hence my question.

Edit: None of the answers in the linked question solve this problem. There is no mention of matching a colon character, and trying to adapt the answers does not work either.

@WiktorStribiżew Thanks, do you want to add this as an answer with some explanation? — FreelanceConsultant, Mar 11 '22 at 11:12
Perhaps you expected it to behave like a glob? Regex and wildcards follow different rules and you'll be hard pressed to find two tools following the same rules for regex. — Sundeep, Mar 11 '22 at 11:23
See [Regular expression to match string starting with a specific word](https://stackoverflow.com/questions/1240504/regular-expression-to-match-string-starting-with-a-specific-word) — The fourth bird, Mar 11 '22 at 11:25

score 0 · Answer 1 · answered Mar 11 '22 at 11:13

0

You can use

grep -rI '^:.*mystring' file

Details:

^ - start of string
: - a colon
.* - any zero or more chars
mystring - a string.

answered Mar 11 '22 at 11:13

Wiktor Stribiżew

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Also, in case you are not using a GNU `grep`, see [Grep regular expression not working as expected](https://stackoverflow.com/questions/51240179/grep-regular-expression-not-working-as-expected) – Wiktor Stribiżew Mar 11 '22 at 11:22
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Bizzarely this actually doesn't work on the system I am using. Sorry for the delay in reply I was away from my desk – FreelanceConsultant Mar 11 '22 at 12:39
Try searching for `: public className` and compare to grepping for `^:.*className' - unless there is a bug in my version of grep they give different results – FreelanceConsultant Mar 11 '22 at 12:40
@FreelanceConsultant See [this online demo](https://ideone.com/RNYFWG). Install a GNU `grep`. – Wiktor Stribiżew Mar 11 '22 at 13:38
Unfortunatly I can't install anything on this machine as I don't have admin access for it – FreelanceConsultant Mar 12 '22 at 20:39
@FreelanceConsultant Ok, then use `awk`: `awk '/^:/ && index(tolower($0), "classname")' file` – Wiktor Stribiżew Mar 12 '22 at 21:07

Grep: How to grep for a string containing a colon

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