rsync can be applied as such. Either I don't understand you and am missing something or you could use the following link: https://linux.die.net/man/1/rsync
Anyhow: Good stuf you're making && godspeed at your venture. ^_^
When I was investigating backup solutions in 2010, I did read about rsync and had read a few negative reviews saying that user's had their backups corrupted (by rsync) and that they were unable to restore their backups. However, looking now I am unable to find those reviews. So, likely either those issues were fixed in a newer version of rsync or I am not remembering the posts correctly.