I ran into a situation recently where I had to copy a database, but didn’t have the disk space for a full dump. Instead of rsync or scp (which can be done over netcat as well), I opted to pipe the output of mysqldump to netcat and transfer the data directly to the other server.
My setup was Ubuntu server 12.04 and Linux Mint 16 (client). First, start netcat on the client machine on an available port (e.g., 1234) and redirect the output to the desired .sql file:
On the server, we’ll route the mysqldump output through a gzip wrapper and into netcat. In this example, the destination machine (above) is 172.21.1.2, and should hopefully be listening on port 1234 already. (It is worthwhile to note that you should supply the MySQL password in the command itself, rather than just using the “-p” option. The password prompt will be transmitted to the listening machine, which will end the netcat session. Security-conscious users can enter a space before the command to keep it from being stored in bash history.)