+backup suffix used with the --backup (-b) option. The default suffix is a ~
+if no --backup-dir was specified, otherwise it is an empty string.
+
+dit(bf(-u, --update)) This forces rsync to skip any files which exist on
+the destination and have a modified time that is newer than the source
+file. (If an existing destination file has a modify time equal to the
+source file's, it will be updated if the sizes are different.)
+
+In the current implementation of --update, a difference of file format
+between the sender and receiver is always
+considered to be important enough for an update, no matter what date
+is on the objects. In other words, if the source has a directory or a
+symlink where the destination has a file, the transfer would occur
+regardless of the timestamps. This might change in the future (feel
+free to comment on this on the mailing list if you have an opinion).
+
+dit(bf(-k, --keep-dirs)) Tell the sending side to keep any directories that
+are encountered. Unlike --recursive, a directory's contents are not copied
+unless the directory was specified on the command-line as either "." or a
+name with a trailing slash (e.g. "foo/"). Without this option or the
+--recursive option, rsync will skip all directories it encounters (and
+output a message to that effect for each one).
+
+dit(bf(-K, --keep-dirlinks)) On the receiving side, if a symlink is
+pointing to a directory, it will be treated as matching a directory
+from the sender.
+
+dit(bf(--inplace)) This causes rsync not to create a new copy of the file
+and then move it into place. Instead rsync will overwrite the existing
+file, meaning that the rsync algorithm can't accomplish the full amount of
+network reduction it might be able to otherwise (since it does not yet try
+to sort data matches). One exception to this is if you combine the option
+with --backup, since rsync is smart enough to use the backup file as the
+basis file for the transfer.
+
+This option is useful for transfer of large files with block-based changes
+or appended data, and also on systems that are disk bound, not network
+bound.
+
+The option implies --partial (since an interrupted transfer does not delete
+the file), but conflicts with --partial-dir. Prior to rsync 2.6.4
+--inplace was also incompatible with --compare-dest, --copy-dest, and
+--link-dest.
+
+WARNING: The file's data will be in an inconsistent state during the
+transfer (and possibly afterward if the transfer gets interrupted), so you
+should not use this option to update files that are in use. Also note that
+rsync will be unable to update a file in-place that is not writable by the
+receiving user.