Find files with nonstandard characters

Question

I seem to have forgotten something for doing regular expressions. I'm trying to use Agent Ransack to find all the files on my Kindle that contain nonstandard characters in the filenames.
Basically, I'd like a list of all files that have something other than A-Z, a-z, 0-9, (aka alphanumeric) periods or underscores.

However I'm not getting proper results when I try to use the regular expression feature in Agent Ransack. Probably because I've never been good at regular expressions.

Could somebody try constructing a search pattern I could try for the program? I'm honestly not sure how to say "Return all files that contain something other than [A-Z]|[a-z]|[0-9]|.|_" without excluding all results that contain those characters since every file will have a period and something in the [a-z] range.

Answer 1

I think it'll be a bit trial and error. Start with something like:

[^a-z0-9 ."'_,-]

And then keep adding the characters that are found that you don't consider non-standard.

Comments

How do I exclude commas from the results? Adding , or \, to the above gives me an error

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You should be able to enter a comma in the list, just make sure the minus sign is last. e.g.
[^a-z0-9 ."'_,-]