#To change all the files to 644 (-rw-r--r--):

find /opt/lampp/htdocs -type f -exec chmod 644 {} \;
find . -type f -exec chmod 644 {} \;

#To change all the directories to 755 (-rwxr-xr-x):

find /opt/lampp/htdocs -type d -exec chmod 755 {} \;