rsync’s  delta‐transfer  algo‐
              rithm  to  a  fixed  value.  It is normally selected based on the
              size of each file being updated.  See the  technical  report  for
              details.

              Beginning in 3.2.3 the SIZE can be specified with a suffix as de‐
              tailed  in the --max‐size option.  Older versions only accepted a
              byte count.

       --rsh=COMMAND, -e
              This option allows you to choose an alternative remote shell pro‐
              gram to use for communication between the local and remote copies
              of rsync.  Typically, rsync is configured to use ssh by  default,
              but you may prefer to use rsh on a local network.

              If  this  option  is used with [user@]host::module/path, then the
              remote shell COMMAND will be used to run an rsync daemon  on  the
              remote host, and all data will be transmitted through that remote
              shell  connection, rather than through a direct socket connection
              to a running rsync daemon on the  remote  host.   See  the  USING
              RSYNC‐DAEMON  FEATURES  VIA  A  REMOTE‐SHELL  CONNECTION  section
              above.

              Beginning with rsync 3.2.0, the RSYNC_PORT  environment  variable
              will  be set when a daemon connection is being made via a remote‐
              shell connection.  It is set to 0 if the default daemon  port  is
              being  assumed,  or it is set to the value of the rsync port that
              was specified via either the --port option or  a  non‐empty  port
              value in an rsync:// URL.  This allows the script to discern if a
              non‐default  port is being requested, allowing for things such as
              an SSL or stunnel helper script to connect to a default or alter‐
              nate port.

              Command‐line arguments are permitted  in  COMMAND  provided  that
              COMMAND is presented to rsync as a single argument.  You must use
              spaces (not tabs or other whitespace) to separate the command and
              args  from  each  other,  and  you can use single‐ and/or double‐
              quotes to preserve spaces in an argument (but  not  backslashes).
              Note  that  doubling a single‐quote inside a single‐quoted string
              gives you a single‐quote; likewise for double‐quotes (though  you
              need  to  pay attention to which quotes your shell is parsing and
              which quotes rsync is parsing).  Some examples:

                  ‐e ’ssh ‐p 2234’
                  ‐e ’ssh ‐o "ProxyCommand nohup ssh firewall nc ‐w1 %h %p"’

              (Note that ssh users can alternately customize site‐specific con‐
              nect options in their .ssh/config file.)

              You can also choose the remote shell program using the  RSYNC_RSH
              environment  variable,  which accepts the same range of values as
              -e.

              See also the --blocking‐io option which is affected by  this  op‐
              tion.

       --rsync‐path=PROGRAM
              Use  this  to specify what program is to be run on the remote ma‐
              chine to start‐up rsync.  Often used when rsync is not in the de‐
              fault    remote‐shell’s    path    (e.g.    --rsync‐path=/usr/lo‐
              cal/bin/rsync).   Note  that  PROGRAM  is  run with the help of a
              shell, so it can be any  program,  script,  or  command  sequence
              you’d care to run, so long as it does not corrupt the standard‐in
              & standard‐out that rsync is using to communicate.

              One tricky example is to set a different default directory on the
              remote machine for use with the --relative option.  For instance:

                  rsync ‐avR ‐‐rsync‐path="cd /a/b && rsync" host:c/d /e/

       --remote‐option=OPTION, -M
              This  option