Stop grep after Nth files matched

Typically, when you get a > in the next line after hitting, it means that one of your quotes isn't closed yet. I couldn't find that mistake in your regex. But you do not need to surround the path /var/www_data/somepath/ with single quotes. I assume there are no unusual characters in somepath?

Anyways, I tested your regex with sed. \d\w look like vim syntax for me, that's why I translated it to ascii (which always works). Also, inside of [] you do not need to escape .:

sed -r "s/'([A-Za-z0-9_-.]+)(@domain.com)'/'adsf'/g" test.dat

Indeed you can use sed or perl for your task. You don't necessarily need grep to generate a file list, unless you have GB of data. Then presorting could result in a speed benefit.

To test your regex, you could do the following:

cd /var/www_data/somepath/
sed -r 's|pattern|replace-pattern|g' a_single_file.php

When you're satisfied with the result, just add the -ibak (--in-place=bak) argument and run it on all files

find . -type f -name '*.php' -o -name '*.ini' -o name '*.conf' -o -name '*.sh' \
-exec sed -r -ibak 's|pattern|replace-pattern|g' '{}' \; 

The original files are being put into <orignalname.php>.bak.

To answer your last question. For this job, grep is the tool you want, you could run it on the .bak files generated by sed above:

grep --recursive --include='*.bak' -E --files-with-matches 'pattern' . > files_fixed.txt

or, simply:

find . -type f -name '*.bak'

{ grep -m1 match; grep -c ''; } <file

That will work w/ GNU grep and an lseek()able infile. The first grep will stop at 1 -match, and the second will -count every line remaining in input.

Without GNU grep:

{ sed '/match/q'; grep -c ''; } <file

Of course, w/ grep you can use any/all of its other options besides, and stopping at one match is not at all necessary.