How to batch update attribute(s) for a selection

[cassb]

Is there an existing script to change or add the value of one or more attributes to a selection of images?

Thanks!
Bryan

[Mario]

You can change the Attributes for any number of files in the Attribute panel. Just select the files you want to change.
See the help for the Attributes panel for details.

If you need to do this from a script, just iterate over the selected files.  Wrap your update into a transaction for better performance and control.