Utility of --backup

[Charles]

 > And let me do what you suggest.  What is the difference, and is --backup
 > better than the other ?

Only in conjunction with -backup-dir, for example

--backup --backup-dir=_Changed and deleted files/2021/Jul/19 at 21:21

The man page's entry for --backup suggests using it with either 
--backup-dir or --suffix

On 19/07/2021 19:22, lisa-asket at perso.be wrote:
> From: Charles via rsync <rsync at lists.samba.org>
> To: rsync at lists.samba.org
> Subject: Re: Utility of --backup
> Date: 19/07/2021 14:26:59 Europe/Paris
> 
>  >IThe --backup option is great for creating "rolling full" backups which
>  >look exactly like the backed up tree except for the existence of the
>  >backup directory
> 
> I am not really understanding the "Rolling Full Backup".  Suppose I have 
> a directory
> and use `rsync -av --progress --log-file="$logfl" "$source" "$destin"`
> 
> And let me do what you suggest.  What is the difference, and is --backup 
> better than the other ?
> 
> Would the command be
> 
> rsync --backup -v --progress --log-file="$logfl" "$source" "$destin"
> 
>  >Here's how a Linux backup directory tree looks as created by backup
>  >utility bung's bu_rsync script
> 
> +-- bin -> usr/bin
> +-- boot
> |   +-- grub
> +-- _Changed and deleted files
> |   +-- 2021
> |   +-- Jul
> |   |   +-- 01 at 17:45
> |   |   |   +-- opt
> |   |   |   |   +-- tomcat
> |   |   |   +-- root
> |   |   |   +-- var
> |   |   |   +-- backups
> |   |   |   +-- cache
> |   |   |   +-- lib
> |   |   |   +-- local
> |   |   |   +-- log
> |   |   |   +-- mail
> |   |   |   +-- spool
> ...
> |   |   +-- 17 at 17:46
> ...
> |   |   +-- 18 at 17:45
> ...
> |   +-- Jun
> ...
> |   +-- 29 at 17:45
> ...
> |   +-- 30 at 17:45
> ...
> +-- dev
> +-- etc
> ...
> 
>  >A "rolling full" backup is great to restore from for small organisations
>  >which do not do enough restores to be well practised because the backup
>  >looks exactly like the source except for the additional "_Changed and
>  >deleted files" directory.
> 
>  >Perfect point in time restores are not possible but adequate
>  >approximations (point in time but with the possibility of some extra
>  >files) can be done by restoring the last backup and then each of the
>  >changed and deleted files sets until the latest set after the desired
>  >point in time
>