I had a need recently to where I needed to grep an Apache httpd log file to see if a certain web subfolder was accessed. I wanted to grep the access log file which has historical and live data coming into it, and found this to be a great solution. Sharing it here in case it helps someone in the future!
In this example,
dd87946d06c23e was the name of the folder I was looking to see was accessed.
tail -f -n 5000 /var/log/httpd/access_log | grep --line-buffered dd87946d06c23e