How to Secure Copy (SCP) files between machines

Copy from another machine to local

scp <username>@<server>:/path/to/file.txt /local/dir

Copy from local machine to remote machine

scp file.txt <username>@<server>:/path/to/directory

Copy full directory from remote host to local

scp -r <username>@<server>:/path/to/directory /local/dir

Copy full directory from local to remote host

scp -r <dirname> <username>@<server>:/path/to/directory

Copy files between 2 remote hosts from local

scp <username>@<server1>:/some/dir/file.txt \ <username>@<server2>:/some/directory/