The --itemize-changes option in rsync is used to provide a detailed summary of the changes that rsync makes to files during synchronization. It's particularly useful when you want to see exactly what modifications are being performed, such as changes to file permissions, ownership, modification times, or content. This option is typically used when debugging synchronization issues, verifying what changes rsync will make, or when you need a precise log of all alterations for audit or review purposes.

Here's an example of the output you might see when using rsync --itemize-changes:

>f+++++++++ newfile.txt
>f..t...... existingfile.txt
>f.s....og. modifiedfile.txt
.d..t...... directory/

The diagram below explains the output of the rsync --itemize-changes command. It breaks down the symbols used to indicate file types (e.g., file, directory, symlink) and actions taken (e.g., sent, received, local changes), along with attributes modified such as permissions, owner, group, and more.