How to use the grep command to search for a line only in certain files?

Question

linux

Let's say I want to find a file that has a certain string in it.
I can
grep -r "string" /path
but there are too many files and I know I need a file. ending in .conf
I tried
grep -r "string" /path/*.conf
but it looked for a directory. ending with .conf

Answer 1

--include

Answer 2

find -type f -name "/путь/*.conf" | xargs -n 10 grep "строка"

Answer 3

find . -regex ".*\.conf" -exec grep -f "тут что ищем" {} \;

you will get the names of the files in which there is a mention of your line
And here is an example if you need to replace
, for example, change one value in all files (the regular expression was written for delbian there are several php.ini)

find . -name 'php.ini' -exec sed -i 's/log_errors = Off/log_errors = On/g' "{}" \;