Macos – Using rsync to synchronise folders without overwriting files of same name on Mac OS X

This is what the man page in CentOS says:

-f, --force
    ignore nonexistent files, never prompt

-r, -R, --recursive
    remove directories and their contents recursively

From what I gather (thanks to some comments below), the following is true for the -r and -f flags:

-r

• recursively deletes content of a directory, including hidden files and sub directories
• depending on your configuration, it may ask for permission (for example, when using the --interactive flag). Some distributions do this by default.
• can be used to remove a directory, if you want to do so, simply give it the path of the directory (for example: /path/to/directory)

-f

• does not recursively delete content of a directory, only removes files that directly match the given path (for example example/file1 or example/*).
• Never deletes sub directories
• Never asks for permission, basically the yes to all in Windows

Below are a few examples, all of them start with the following structure:

example/
  file1
  file2
  file3
  .file
  dir/
    file1
    file2
    file3
    .file

I enabled verbosity and interactive mode by default for these examples. Some distros do this while others don't.

rm example

$ rm example
rm: cannot remove `example': Is a directory

As you can see, rm does not remove directories by default.

rm example -f

$ rm example -f
rm: cannot remove `example': Is a directory

Using the -f flag still doesn't allow it to remove directories.

rm example -r

$ rm example -r
rm: descend into directory `example'? yes
rm: remove regular empty file `example/file3'? yes
  removed `example/file3'
rm: remove regular empty file `example/file2'? yes
  removed `example/file2'
rm: descend into directory `example/dir'? yes
rm: remove regular empty file `example/dir/.file'? yes
  removed `example/dir/.file'
rm: remove regular empty file `example/dir/file3'? yes
  removed `example/dir/file3'
rm: remove regular empty file `example/dir/file2'? yes
  removed `example/dir/file2'
rm: remove regular empty file `example/dir/file1'? yes
  removed `example/dir/file1'
rm: remove directory `example/dir'? yes
  removed directory: `example/dir'
rm: remove regular empty file `example/file1'? yes
  removed `example/file1'
rm: remove directory `example'? yes
  removed directory: `example'

As you can see, you are asked for permission for every single file and directory, hidden files are also removed.

rm example/* -f

$ rm example/* -f
rm: cannot remove `example/dir': Is a directory
removed `example/file1'
removed `example/file2'
removed `example/file3'

Here, you are not asked for permission, directories are not deleted and neither are hidden files.

rm example/* -r

$ rm example/* -r
rm: descend into directory `example/dir'? yes
rm: remove regular empty file `example/dir/.file'? yes
  removed `example/dir/.file'
rm: remove regular empty file `example/dir/file3'? yes
  removed `example/dir/file3'
rm: remove regular empty file `example/dir/file2'? yes
  removed `example/dir/file2'
rm: remove regular empty file `example/dir/file1'? yes
  removed `example/dir/file1'
rm: remove directory `example/dir'? yes
  removed directory: `example/dir'
rm: remove regular empty file `example/.file'? yes
  removed `example/file'
rm: remove regular empty file `example/file1'? yes
  removed `example/file1'
rm: remove regular empty file `example/file2'? yes
  removed `example/file2'
rm: remove regular empty file `example/file3'? yes
  removed `example/file3'

Here, the contents of the example directory (not the directory itself) are removed, including hidden files.