rsync

Option –compare-dest also compare destination files relative to DIR.

If DIR is a relative path, it is relative to the destination directory

So to restore changes between remote DST and current folder . but save restored files in _RESTORED_BACKUP folder:

rsync --dry-run -v -ra -P -i --compare-dest=.. ${DSTHOST}:/backup/ _RESTORED_BACKUP

rsync want to transfer - add -i option (–itemize-changes). Usefull also with -n –dry-run.

Rsync cannot work with two remotes. As workaround SSH tunnel to remote host is created and rsync is spawned locally on src host.

How to rsync files between two remotes?

#!/bin/bash -eux
SOURCE_USER=root
SOURCE_HOST=192.168.179.2
SOURCE_PATH="/public/image.iso"
 
TARGET_USER=root
TARGET_HOST=pve5
TARGET_PATH=/mnt/pve/cephfs/template/iso/
 
# Escape characters:
SOURCE_PATH=$(printf %q "$SOURCE_PATH")
TARGET_PATH=$(printf %s "$TARGET_PATH")
 
 
OPTS="--recursive --times --partial --progress --verbose --update --archive --stats"
OPTS="${OPTS} --bwlimit=400"
OPTS="${OPTS} --compress --compress-level=9"
 
# Test connection to accept remote host key
ssh -l $TARGET_USER -A -R localhost:22000:$TARGET_HOST:22 $SOURCE_USER@$SOURCE_HOST "ssh localhost -p 22000 -l root whoami"
 
ssh -l $TARGET_USER -A -R localhost:22000:$TARGET_HOST:22 \
$SOURCE_USER@$SOURCE_HOST "rsync -e 'ssh -p 22000' ${OPTS} \
${SOURCE_PATH} \
$TARGET_USER@localhost:${TARGET_PATH}"