Last updated about 4 weeks ago

rsync (Remote Sync)

From man rsync:

Rsync is a fast and extraordinarily versatile file copying tool.

It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It’s famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination.

Note the trailing slash; without that it will put folder1 inside folder2