# Using regular expressions w/ "Text file to tag" conversion
**URL:** https://community.mp3tag.de/t/using-regular-expressions-w-text-file-to-tag-conversion/70001
**Category:** Support
**Created:** [October 15, 2025, 1:55am UTC](https://community.mp3tag.de/t/using-regular-expressions-w-text-file-to-tag-conversion/70001 "2025-10-15T01:55:14Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@JimS](https://community.mp3tag.de/u/JimS)
#### Post date: [October 15, 2025, 1:55am UTC](https://community.mp3tag.de/t/using-regular-expressions-w-text-file-to-tag-conversion/70001/1 "2025-10-15T01:55:14Z")
I want to extract the year (e.g. 1967) from a text file of song information (a single line per mp3). A solution I finally came up with was to import the line into the year tag location and then apply a **tag to tag** conversion using **$regexp(%year%,'^._(\d\d\d\d).\*_$',$1)**. But I could not find a way to do it directly. I was looking for something like, **$regexp(%line\_from\_file%,'^._(\d\d\d\d).\*_$',%year%)** but I could not find an appropriate tag or mapping to reference the text file line.
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [October 15, 2025, 6:07am UTC](https://community.mp3tag.de/t/using-regular-expressions-w-text-file-to-tag-conversion/70001/2 "2025-10-15T06:07:05Z")
> [@JimS](#):
>
> But I could not find a way to do it directly.
It is not possible to mix functions of a generating format string with the field assignment in a matching format string.
The way to import the data "as is" first into a field and then treat it is the only way.
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [November 14, 2025, 6:07am UTC](https://community.mp3tag.de/t/using-regular-expressions-w-text-file-to-tag-conversion/70001/3 "2025-11-14T06:07:20Z")
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