The configuration line is CustomLog "|$/bin/sed -u -E 's/(ticket)(=|%3D)[a-zA-Z0-9%]+/\1\2***/g' >> /dev/stdout" json. The goal is to replace query params like ticket=123 to ticket=***.

I’ve tried without 's, ', \. None of them work.

The questions are:

1. Why do we need 's and '? The ' is inside ", Isn’t it unnecessary to do so?
2. Why do we need \ instead of just \? I thought the first backslash is in the context of Apache configuration to escape the following backslash so that \ actually becomes when passed to the shell indicated by $ in the beginning.