rsync - Nov 2010 - DO NOT REPLY [Bug 7823] New: Documentation enhancement for --inplace option

https://bugzilla.samba.org/show_bug.cgi?id=7823

           Summary: Documentation enhancement for --inplace option
           Product: rsync
           Version: 3.1.0
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: minor
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: erik at logtenberg.eu
         QAContact: rsync-qa at samba.org


The man page lists 5 limitations of the --inplace option, one of those is:

(4) a file that does not have write permissions can not be updated

A small enhancement of the man page would be to specify that this limitation
doesn't count for the root user. In other words the limitation is not that
rsync would check the file permissions and refuse if it doesn't have +w,
instead rsync simply tries to write anyway and if that works (i.e. the user is
somehow allowed to write to that file regardless of file permissions) all is
well.

In my case, /etc/shadow can in fact perfectly be backed up with rsync
--inplace, despite the -r-------- permissions. In order to be able to read that
file, rsync was running as root anyway.

Secondly, the man page gives a hint for possible use cases of --inplace:

This option is useful for transferring large files with block-based changes or
appended data, and also on systems that are disk bound, not network bound.

A use case that will become more and more relevant these days and in the near
future is the use of copy-on-write filesystems, that also support snapshots,
like btrfs. In that context using --inplace can seriously increase disk space
efficiency, because the fs then only has to store the changed blocks.


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https://bugzilla.samba.org/show_bug.cgi?id=7823


wayned at samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




------- Comment #1 from wayned at samba.org  2011-01-01 20:19 CST -------
Thanks -- I've clarified those issues in the master branch of git.


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