tar + netcat = very fast copy

Apr 13, 2015 • alan


I reformatted a hard disk this weekend. In the process, I needed to copy a bunch of files from one machine to the other. Since both of these machines were smaller embedded devices, neither one of them had very capable CPUs. So I wanted to copy all of the files without compression or encryption.

Normally, I would use “rsync -avz --delete --progress user@other:/remote/path/ /local/path/“, but this does both compression (-z) and encryption (via rsync-over-ssh).

Here’s what I ended up with. It did not disappoint.

Step 1 – On the machine being restored:

box1$ netcat -l -p 2020 | tar --numeric-owner -xvf -

Step 2 – On the machine with the backup:

box2$ tar --numeric-owner -cvf - | netcat -w3 box1 2020