So you have a directory and you want to change permissions on all files in the directory or directories but not the directories themselve it’s easy in linux
Assume the directory I want to start on is /local and I want everything under this directory to be chmod 644 then I would run
find /local -type f -exec chmod 644 {} \;
Or if I wanted to print out results first to check them
find /local -type f -print
Or if I wanted to change the owner to bob:bob
find /local -type f -exec chown bob:bob {} \;
How about you want to change directories only to 755?
find /local -type d -exec chmod 755 {} \;