Can rsync detect changes in owner/group or perms

rsync

Can rsync be used to create and maintain an exact copy of a filesystem remotely, detecting owner or group or permission changes too?

My current "rsync –del –numeric-ids -a something/ root@host:/somewhere/" only syncs by time or (or –checksum). If, say, only owner changes nothing is syncd. The workaround is to delete everything and resync, wearing out the targets flash storage.

If not, is there another way?

My goal is to be able to have networked hdd with that is an exact duplicate and can simply be plugged into the source machine in the event of a device/fs failure, or (my main reason) to sync an embedded os accross the network that has had only minor (but numerous untracked) tweeks.

EDIT: Original command used root@host not user@host

Best Answer

Check out this similar question.

You can use the following flags to preserve that specific information:

-p Preserve permissions

-o Preserve owner

-g Preserve group

-X Preserve Extended Attributes

-A Preserve File ACLs

Related Solutions

Rsync — Itemized List of Changes

from the man page of rsync:

-F same as --filter='dir-merge /.rsync-filter' repeated: --filter='- .rsync-filter'

        --exclude=PATTERN       exclude files matching PATTERN
        --exclude-from=FILE     read exclude patterns from FILE
        --include=PATTERN       don't exclude files matching PATTERN
        --include-from=FILE     read include patterns from FILE
        --files-from=FILE       read list of source-file names from FILE

so run rsync -i first and output it to a file and use --files-from option or you can use find utility for finding the last modified file and then rsync them. see https://serverfault.com/questions/115945/synchronizing-very-large-folder-structures

Rsync ignore owner, group, time, and perms

I think you can use the -no- options to rsync to NOT copy the ownership or permissions of the files you're sync'ing.

Excerpt From rsync Man Page

--no-OPTION
       You may turn off one or more implied options by prefixing the option 
       name with "no-".  Not all options may be pre‐fixed  with  a  "no-":  
       only options that are implied by other options (e.g. --no-D, 
       --no-perms) or have different defaults in various circumstances (e.g. 
       --no-whole-file, --no-blocking-io, --no-dirs).  You may specify 
       either the short or the long option name after the "no-" prefix (e.g. 
       --no-R is the same as --no-relative).

       For example: if you want to use -a (--archive) but don’t want -o 
       (--owner), instead of converting -a into -rlptgD, you could specify 
       -a --no-o (or -a --no-owner).

       The order of the options is important:  if you specify --no-r -a, the 
       -r option would end up being turned on,  the opposite  of  -a  
       --no-r.   Note  also  that the side-effects of the --files-from 
       option are NOT positional, as it affects the default state of several 
       options and slightly changes the meaning of -a (see the  --files-from
       option for more details).

Ownership & Permissions

Looking through the man page I believe you'd want to use something like this:

$ rsync -avz --no-perms --no-owner --no-group ...

To delete files that don't exist you can use the --delete switch:

$ rsync -avz --no-perms --no-owner --no-group --delete ....

Timestamps

As for the timestamp I don't see a way to keep this without altering how you'd do the comparison of SOURCE vs. DEST files. You might want to tell rsync to ignore timestamps using this switch:

-I, --ignore-times
       Normally  rsync will skip any files that are already the same size 
       and have the same modification timestamp.  This option turns off this 
       "quick check" behavior, causing all files to be updated.

Update

For timestamps, --no-times might do what you're looking for.