Copy or rsync command

Question

The following command is working as expected...

cp -ur /home/abc/* /mnt/windowsabc/

Does rsync has any advantage over it? Is there a better way

Answer 1

For a local copy, the only advantage of rsync is that it will avoid copying if the file already exists in the destination directory. The definition of "already exists" is (a) same file name (b) same size (c) same timestamp. (Maybe same owner/group; I am not sure...)

The "rsync algorithm" is great for incremental updates of a file over a slow network link, but it will not buy you much for a local copy, as it needs to read the existing (partial) file to run it's "diff" computation.

So if you are running this sort of command frequently, and the set of changed files is small relative to the total number of files, you should find that rsync is faster than cp. (Also rsync has a --delete option that you might find useful.)

Answer 2

Especially if you use a copy-on-write filesystem like BTRFS or ZFS, rsync is much better.

I use BTRFS, and I have this in my ~/.bashrc:

alias cp="rsync -ah --inplace --no-whole-file --info=progress2"

The important flag here for CoW FSs like BTRFS is --inplace because it only copies the changed part of the files, doesn't create new for small changes between files inodes, etc. See this.