Hi. I took a break from tagging files that I record off FM and I forgot my way of working.
I have the date recorded in the comment field as "20240314" (which would be YYYYMMDD).
I want to rename the files from "20240314" - Title to "2024-03-14 - Title"
So is there something I can do with Tag->Filename to rename the files?
You can try
$regexp(%COMMENT%,(\d{4})(\d{2})(\d{2}),$1-$2-$3) - %TITLE%

This only works correctly if the numbers in COMMENT are really arranged as YYYYMMDD.
Since I love regex I thought I'd try to improve yours a bit.
^((?:19|20)\d{2})((?:0[1-9]|1[0-2]))(\d{2})$
This only matches when the first 4 digits start with 19 or 20 (for 19th and 20th century) and the 2 digits that follow must be between 01 and 12 for months.
The only cases where this still might fail is when you have switched days and months and the day is within the 01-12 range.
I tried LyricsLover's idea and it worked perfectly. Thank you