underlying question: Is there a way to operate on text within a regex match? I.e. is there an analog to the 'g' command that operates on match substrings instead of lines
usecases: One example of this would be if you replace a pattern within a pattern without a huge amount of regex gymnastics (which are often possible with much effort). A specific example might be replace spaces with tabs but only in text matching a regex.
field1 field2 field3 field4 field with spaces
Another specific example would be if you wanted to replace - with _ but only in text inside quotes
You should name your file [something something something] and name their file [a b c d]