Custom action to edit all records at once

Custom action to edit all records at once

Hi everyone,
 
I know how to script a custom action and add it to a view, so I can bulk edit many records at a time.  But it seems to me that it is limited to 200 records at a time.  I have more than 5000 records and need to do a lot of bulk editing.

How can I run a script through all my records, in order to edit some fields, in a one-time operation?

Thanks

Patrice