rsync(1) -avzn --delete
a fast, versatile, remote (and local) file-copying tool
-a, --archive
       This is equivalent to -rlptgoD. It is a quick way  of  saying  you  want  recursion  and  want  to
       preserve  almost  everything  (with -H being a notable omission).  The only exception to the above
       equivalence is when --files-from is specified, in which case -r is not implied.

       Note that -a does not preserve hardlinks, because finding multiply-linked files is expensive.  You
       must separately specify -H.
-v, --verbose
       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.
-z, --compress
       With  this  option, rsync compresses the file data as it is sent to the destination machine, which
       reduces the amount of data being transmitted -- something that is useful over a slow connection.

       Note that this option typically achieves better compression ratios than can be achieved by using a
       compressing  remote  shell  or  a compressing transport because it takes advantage of the implicit
       information in the matching data blocks that are not explicitly sent over the connection.

       See the --skip-compress option for the default list of file suffixes that will not be compressed.
-n, --dry-run
       This makes rsync perform a trial run that doesn’t make any changes (and produces mostly  the  same
       output  as a real run).  It is most commonly used in combination with the -v, --verbose and/or -i,
       --itemize-changes options to see what an rsync command is going to do before one actually runs it.

       The output of --itemize-changes is supposed to be exactly the same on a dry run and  a  subsequent
       real  run  (barring  intentional  trickery  and  system call failures); if it isn’t, that’s a bug.
       Other output should be mostly unchanged, but may differ in some areas.  Notably, a  dry  run  does
       not send the actual data for file transfers, so --progress has no effect, the "bytes sent", "bytes
       received", "literal data", and "matched data" statistics are too small, and the "speedup" value is
       equivalent to a run where no file transfers were needed.
       This tells rsync to delete extraneous files from the receiving  side  (ones  that  aren’t  on  the
       sending  side),  but  only  for  the directories that are being synchronized.  You must have asked
       rsync to send the whole directory (e.g.  "dir"  or  "dir/")  without  using  a  wildcard  for  the
       directory’s  contents  (e.g.  "dir/*")  since the wildcard is expanded by the shell and rsync thus
       gets a request to transfer individual files, not the files’  parent  directory.   Files  that  are
       excluded   from   the   transfer  are  also  excluded  from  being  deleted  unless  you  use  the
       --delete-excluded option or mark the  rules  as  only  matching  on  the  sending  side  (see  the
       include/exclude modifiers in the FILTER RULES section).

              Prior  to rsync 2.6.7, this option would have no effect unless --recursive was enabled.  Beginning
              with 2.6.7, deletions will also occur when --dirs (-d) is enabled, but only for directories  whose
              contents are being copied.

              This option can be dangerous if used incorrectly!  It is a very good idea to first try a run using
              the --dry-run option (-n) to see what files are going to be deleted.

              If the sending side detects any I/O errors, then the deletion of any files at the destination will
              be  automatically  disabled. This is to prevent temporary filesystem failures (such as NFS errors)
              on the sending side from causing a massive deletion of files on the destination.  You can override
              this with the --ignore-errors option.

              The  --delete  option  may  be combined with one of the --delete-WHEN options without conflict, as
              well as --delete-excluded.  However, if none of the --delete-WHEN  options  are  specified,  rsync
              will  choose  the  --delete-during  algorithm  when  talking  to  rsync  3.0.0  or  newer, and the
              --delete-before  algorithm  when  talking  to  an  older  rsync.   See  also  --delete-delay   and
source manpages: rsync