Thanks. I had a look at that link and I’ll try DupeGuru and FSLint, however I’m pretty sure I tried them both about a year ago and they did not satisfy my needs. I don’t remember now what their limitations were, but I think they could not read all of the files in an HFS+ file system if the filenames, or folder names contained commas or slashes. I run into this problem often when I’m cleaning up old Mac Time-Machine backups from Macs that have been disposed of. Or different backups on different drives of the same Mac. They are difficult to deal with.
The most common need I have is when I have 8-10 old external USB drives that have various chaotic backup sets on them and I just need to check if all the files on (for example) drive A are also present on drive B, and if so then delete all files on Drive A if there is a copy of them on Drive B.
I need the duplicate finder to locate the duplicates and output the results as a csv or txt file.
I then use a macro that I have written to sort through the list of duplicates and delete the files from Drive A if there is a copy of the file on Drive B.
It is common for me to have results where I need to delete 500,000 files or more from one of the drives. It would take an impossibly long time to do that manually even if I could delete one every 5 seconds or so. Therefore I need an absolutely bullet-proof, reliable, automatic method of looking through each group of files and selecting which files need to be deleted. My macro does this even though it might take a hour or two.
I’ll try DupeGuru and FSLint again but I don’t think they were adequate for my needs.