How to set chmod for a folder and files separately in Linux

source:
http://stackoverflow.com/questions/3740152/how-to-set-chmod-for-a-folder-and-all-of-its-subfolders-and-files-in-linux-ubunt

I suspect what you really want to do is set the directories to 755 and either leave the files alone or set them to 644. For this, you can use the find command. For example:
To change all the directories to 755 (-rwxr-xr-x):

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

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

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