How To Synchronize Directories in two different external hard disks? I have few big folders "cosmo_sim_9", "cosmo_sim_10".... in one of my external hard disk, and a old copy of this on another external hard disk. I want to Synchronize old directories with the new one(recursively), but without overwriting already existing files(for saving time). How can I do this? My os is Fedora 20.

use `rsync`:


rsync -a --ignore-existing cosmo_sim_9 /dest/disk/cosmo_sim_9


`--ignore-existing` will cause it to skip existing files on the destination, `-a` will make it recursive, preserving if possible permission/ownership/group/timestamp/links/special devices.

you can do it for all directories by using a bash `for` loop:


for dir in cosmo_sim_* ; do
rsync -a --ignore-existing "$dir" "/dest/disk/$dir"
done