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Does anyone know where I can find the docs describing Regex parsing capabilities of macOS search fields?

What I mean, I'd like to read about the regex syntax rules that are allowed and parsed by the search field. For example, what I didn't know until today that, in macOS Preview (or any other application with a standard search field, guessing) we can use input like this:

"\s" AND "an" AND "\s"

This works and hints that search fields interpret more regex then we know, and this is what I want to read/find out about. The example above searches for "an" with one trailing and leading whitespace character \s within a opened document.

I'd like to know more about those grouping rules and regex characters wrapping/escaping so it can be correctly parsed. Also does this format of input apply to systemwide search fields of any application?

I can't find any docs describing these features and was found only this on developer.apple.com library instead.

Below you can see an example of default search behaviour for a "an" word within a PDF document, it shows all "an" occurences in the results, regardless if you put a space before the "an" word, so your input is " an "

enter image description here

When we put "\s" AND "an" AND "\s" into the search field we get the more desired search result

regex input search field behaviour

This makes a huge difference for searches containing common words!

In short: I'd like to know more about the functionality you see above. Where can I find any (official) documentation about it?

The answers provided (so far) are not answering my question, thank you for them though - aggregating more related information is good.

PJJ
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  • Will this [link](https://developer.apple.com/library/content/documentation/OpenSource/Conceptual/ShellScripting/RegularExpressionsUnfettered/RegularExpressionsUnfettered.html) be of any help to you? – Denis Rasulev Dec 27 '16 at 13:43
  • Hi Denis, thank you for the link- but this is more or less the posix regex manual ;-) and if you look carefully into my example above- its not posix regex- since the common syntax isn't working and that is why the question is here. Im not sure if words like AND OR are in posix regex (correct me, if i'm wrong) anyways. That being said- I can't find the specifics of the syntax for this kind of search field. It is (probably) an instance of https://developer.apple.com/reference/appkit/nssearchfield#overview (guess) but I can't dig out the regex specifics. – PJJ Dec 29 '16 at 06:28
  • Are you sure that we’re talking about regex here? I tried your example in Preview, and a few regex variations, but none of them seemed to behave as a proper regular expression. That doesn’t answer your question, but might help in looking in the right place. – Manngo Jan 17 '17 at 11:13
  • Yes, you are right - and this is what I want to find out! Where is a document describing what kind of syntax is parsed and how? It's not posix regex, but it's regex-ish enough, so what is it? :) – PJJ Jan 17 '17 at 22:24
  • Actually, your example `"\s" AND "an" AND "\s"` above is incorrect. At least in my version of Preview (macOS 10.15), `"\s" AND "an" AND "\s"` and simply searching `"an"` (with quotes) give the exact same result with respect to finding the word "an" (surrounded by spaces). What including `"AND \s"` does is to add the additional requirement that an "S" (again with leading and trailing spaces) should _also_ be present somewhere in the document, but without any restriction as to _where_. The backslash ("\") appears to be ignored completely. – gaspanic Nov 19 '20 at 14:01
  • Here is a practical question with general answers to your problem. [How can I find an exact string in file contents across many folders from the command line on macOS?](https://apple.stackexchange.com/a/391925/5472) – bmike Nov 19 '20 at 14:56

3 Answers3

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I don't know if you discovered this already but you just need to click on the magnifying glass in the search field, it has a little down-pointing caret which is the clue, see this screenshot:

enter image description here

After clicking choose Insert Pattern and you get a range of options:

This is basically user-friendly regex, i.e. you get tokens you can easily arrange into quite powerful search patterns.

enter image description here

The example in the screenshot is TextEdit however this option doesn't appear to be available in Preview.

Demian Turner
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    Hi- thank you for the long answer, BUT this is TextEdit you are showing... not the system-default search window like the one in Preview option, therefore it is not the answer i'm looking for. The search Window I mean is (highly probable) an instance of https://developer.apple.com/reference/appkit/nssearchfield#overview – PJJ Dec 29 '16 at 06:15
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This Apple Support article on how to Narrow your search results on Mac is the most detailed documentation I have been able to find on Finder searches. While the OP is mainly asking about regular expression searches in Preview, the question title brought me here looking for the same information for Finder searches.

The last section on boolean operators (Search using AND, OR, and NOT) is relevant also for Preview, although their utility for text search is rather questionable. Regular expressions are not mentioned, so I suppose these are not supported in the macOS search fields.

gaspanic
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  • I’m so happy Apple is updating the documentation on spotlight. [Having two search languages included](https://apple.stackexchange.com/a/391925/5472) makes it hard to use on occasion. – bmike Nov 19 '20 at 14:28
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This isn't regular expressions; I'm afraid you've faked yourself out. in most of Apple's document apps, there's a distinction between search for "..." (placed within quotes) ... (entered without quotes). The first will search for the enclosed text as a word; the second searches for the text without regarding word boundaries.

So, when we enter the following:

"\s" AND "an" AND "\s"

the parser searches for a literal word s (ignoring the backslash), then the word an then another literal word s. Since it's extremely unlikely to find 's' as an independent word, the result is exactly the same as if we had merely entered:

"an"

but different from what happens if we enter:

an

Confusing, I know...

Ted Wrigley
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  • Actually, `\s` is not assumed to be a control character. As I also wrote in a comment to the OPs question, `"\s"` searches for the word `s`, completely ignoring the backslash character. – gaspanic Nov 19 '20 at 16:09
  • @gaspanic: Ah, that makes sense; thanks. I'll edit it in. – Ted Wrigley Nov 19 '20 at 16:24
  • Gentelmen, I think you are right here; I might have confused myself into thinking it is actually RE - BUT - have you made any test within recent macOS (BigSur/Catalina)? – PJJ Mar 15 '21 at 12:49