This tells rsync to copy directories recursively. See also --dirs (-d).
Beginning with rsync 3.0.0, the recursive algorithm used is now an incremental scan that uses much
less memory than before and begins the transfer after the scanning of the first few directories
have been completed. This incremental scan only affects our recursion algorithm, and does not
change a non-recursive transfer. It is also only possible when both ends of the transfer are at
least version 3.0.0.
Some options require rsync to know the full file list, so these options disable the incremental
recursion mode. These include: --delete-before, --delete-after, --prune-empty-dirs, and
--delay-updates. Because of this, the default delete mode when you specify --delete is now
--delete-during when both ends of the connection are at least 3.0.0 (use --del or --delete-during
to request this improved deletion mode explicitly). See also the --delete-delay option that is a
better choice than using --delete-after.
Incremental recursion can be disabled using the --no-inc-recursive option or its shorter --no-i-r
This option increases the amount of information you are given during the transfer. By default,
rsync works silently. A single -v will give you information about what files are being transferred
and a brief summary at the end. Two -v options will give you information on what files are being
skipped and slightly more information at the end. More than two -v options should only be used if
you are debugging rsync.
Note that the names of the transferred files that are output are done using a default --out-format
of "%n%L", which tells you just the name of the file and, if the item is a link, where it points.
At the single -v level of verbosity, this does not mention when a file gets its attributes
changed. If you ask for an itemized list of changed attributes (either --itemize-changes or
adding "%i" to the --out-format setting), the output (on the client) increases to mention all
items that are changed in any way. See the --out-format option for more details.