Here is how to do it
cp -RfXv "[source folder]" [destination directory]/[foldername]/
cp - is the command forTerminal to copy.
R - is for Recursive, and will force the copy command to not only hit folders, but all items within, including subfolders.
f - forces Terminal to copy everything without stopping.
X - tells Terminal to overwrite existing files.
v - puts the command into verbose mode, this way you'll see a scrolling list of what is actually happening as it works
Once you hit return, you should start seeing a list of files start scrolling across your screen!
Though I used 10.7 this should work no problem in Snow Leopard 10.6 , Mountain Lion 10.8, Mavericks 10.9, Yosemite 10.10, or El Capitan 10.11
Though I used 10.7 this should work no problem in Snow Leopard 10.6 , Mountain Lion 10.8, Mavericks 10.9, Yosemite 10.10, or El Capitan 10.11