Terminal command that is the same as copy paste in Finder?
If you want to preserve file attributes, symbolic links, and recursive structure, rsync should suffice:

rsync -a ~/somefolder /Volumes/SomeUSB/


The -a (archive) flag is a shortcut for the following rsync options:


  --recursive recurse into directories
  --links copy symlinks as symlinks
  --perms preserve permissions
  --times preserve times
  --group sets the group of the destination file to be the same as the source file
  --owner sets the owner of the destination file to be the same as the source file (if you're copying to a remote system, the remote SSH user will need to have superuser status for this)
  --devices rsync will transfer character and block device files to the remote system.