-u, --update
Update the index just where it already has an entry matching
<pathspec>. This removes as well as modifies index entries to match
the working tree, but adds no new files.
If no <pathspec> is given when -u option is used, all tracked files
in the entire working tree are updated (old versions of Git used to
limit the update to the current directory and its subdirectories).
-A
-A, --all, --no-ignore-removal
Update the index not only where the working tree has a file
matching <pathspec> but also where the index already has an entry.
This adds, modifies, and removes index entries to match the working
tree.
If no <pathspec> is given when -A option is used, all files in the
entire working tree are updated (old versions of Git used to limit
the update to the current directory and its subdirectories).