Can rsync be configured to avoid modifying subdirectories not found in the source folder?

Question

I am having a hard time figuring out exactly how to run rsync to get it to do what I need it to do. Basically what I need is as follows given a single source folder with multiple sub-directories:

-If files for a given subdirectory are changed in the source folder, sync those changes to the destination (update files and delete files not found in the source folder any longer).

-If a folder is found in the source but not the destination, sync the folder and all of its contents to the destination.

-If a folder is found in the destination but not in the source, do nothing (e.g. don't delete it).

This is what the directory structure would look like:

Source Folder
   Folder 1
      File 1 unchanged.txt
   Folder 2
      File 2 newer.txt
   Folder 3
      File 3.txt

Destination Folder
   Folder 1
      File 1 unchanged.txt
   Folder 2
      File 2 old.txt (to be replaced with File 2 newer.txt)
   (Folder 3 not yet in destination, to be added from source)
   Folder X (not in source, to be left untouched)

Answer 1

According to man rsync you can use:

--exclude=PATTERN

Or your list is too large you can use :

--exclude-from=FILE 

Answer 2

What you describe is the default standard behavior for rsync.

If you wanted a different behavior you would have to use one of the --delete options.

This is a test that proves my point:

 $ mkdir tmp1
 $ mkdir tmp2
 $ mkdir tmp1/1
 $ mkdir tmp1/2
 $ mkdir tmp2/1
 $ mkdir tmp2/X
 $ touch tmp1/1/1.txt
 $ touch tmp1/2/2.txt
 $ rsync -avz tmp1 tmp2
 sending incremental file list
 tmp1/
 tmp1/1/
 tmp1/1/1.txt
 tmp1/2/
 tmp1/2/2.txt

 sent 208 bytes  received 62 bytes  540.00 bytes/sec
 total size is 0  speedup is 0.00
 $ ls tmp2
 1  tmp1  X

You can see that directory X is there, untouched.

If you are using it as a daemon, maybe your rsync is applying options from a config file.

Look at /etc/rsyncd.conf to see if any delete options are set there or at rsyncd.conf at the home directory of the user that is launching the rsync