mv: do not override destination file that is newer than source file (update move)

mv does not support the update option, unlike rsync and cp. If your version of coreutils does support it, using cp (followed by rm) is the easiest way to perform an update move operation:

unix mv command without overriding existing files

Per default, mv will override existing files with the same name. To rename existing files with the same name instead, use the backup parameter.
mv --backup=numbered
The resulting file name pattern is [filename].[extension].~[number]~, e.g. image.jpg.~1~. Note that these files can be recognized as recycle or backup files by mistake. In this case they might be hidden by your file manager.