-Beginning with 2.6.4, rsync does file deletions on the receiving side
-incrementally as each directory is being transferred (which makes the
-transfer more efficient than a separate delete pass before or after the
-transfer). If you are sending files to an older rsync, --delete will
-behave as --delete-before (see below). See also --delete-after.
-
-dit(bf(--delete-before)) Request that the file-deletions on the receving
-side be done prior to starting the transfer, not incrementally as the
-transfer happens. Implies --delete.
-
-One reason to use --delete-before is if the filesystem is tight for space
+If you don't specify --delete-during (--del) or --delete-after, the
+file deletions will be done before the first file is transferred.
+This is helpful if the filesystem is tight for space