NameChanger is designed for the sole purpose of renaming a list of files. To install just download the zip, open it and drag the app to your Applications Folder.
Add the files through the GUI or drag and drop files directly onto the App. These original filenames show up in the Original Filename column. Grayed out rows indicate files that you do not have permissions to change. Next select how to change the file names:
= Replace First Occurrence = Replace Last Occurrence = Replace All Occurrences = Wildcard = Append = Prepend = Date = Sequence = Character Removal = Regular Expression = Change Case
As text is entered into the appropriate text fields the resulting filenames appear in the Renamed Filename column. As you type each row is updated to reflect the changes you will make. Finally click the Rename button, and all your files will be renamed as displayed. You will be informed of any files that could not be modified.