Filtering out differently styled track numbers in filename

[LyricsLover]

@ragtag

Could you please confirm whether parenthesis are to be used whenever an regular expression operator, such as one of the following, are deployed:

No, the parenthesis are there to "collect/remember" the matched digits or characters.
For example, if you want to replace the matched characters with some other values, you need the parenthesis. They build groups for later use.

@ohrenkino gave you a solution for filenames, using such parenthesis:

Insert text with a regular expression in the filename

If you want to keep the number, then you have to tell MP3tag that it should remember it - which is done by enclosing the pattern in parenthesis. So for something like 101. My music file which should become 1-01. My music file Try: Search pattern: ^(\d)(.*) Replace string: $1-$2 Further information about regular expressions can be found in the documentation:

If you want so search for parenthesis as ordinary character, you have to escape them like this \( for an opening bracket and \) for a closing bracket