# Problem with $regexp in an Action

**URL:** <https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177>\
**Category:** Support\
**Created:** [August 15, 2016, 1:40am UTC](https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177 "2016-08-15T01:40:55Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![ms6676749](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/b4bc9f/32.png) [@ms6676749](https://community.mp3tag.de/u/ms6676749)\
**Post date:** [August 15, 2016, 1:40am UTC](https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177/1 "2016-08-15T01:40:55Z")

</div>

I'm trying to extract %GUEST ARTIST% from the following %title%:

Keep On Movin' (feat. Inga Lühning)

```
[#0]
T=5
F=GUEST ARTIST
1=$regexp(%title%,(^.*)feat\\\\. (.*?)\\\\),$2)

```

In Notepad++, the regexp **(^._)feat. (._?))** returns (via **$2** ): Inga Lühning

However, under mp3tag's format value action for %GUEST ARTIST%, **$regexp(%title%,(^._)feat. (._?)),$2)** it returns: ,$2)

It is the same when the regexp is encased in quotation marks.

The problem with Guess Value is that the term "feat." can be variable like "ft.", "featuring", etc. I can use "|" in regexp to enable lookup of such variations of "feat." To my understanding, this is not possible with guess value.

---

<div class="post-metadata">

**Author:** ![ohrenkino](https://community.mp3tag.de/user_avatar/community.mp3tag.de/ohrenkino/32/4843_2.png) [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)\
**Post date:** [August 15, 2016, 3:15am UTC](https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177/2 "2016-08-15T03:15:15Z")

</div>

> [@ms6676749](#):
>
> ...  
> However, under mp3tag's format value action for %GUEST ARTIST%, **$regexp(%title%,(^._)feat. (._?)),$2)** it returns: ,$2)
> 
> It is the same when the regexp is encased in quotation marks.  
> ...

I think that this expression works:

$regexp(%title%,'^._feat. (._))',$1)

---

<div class="post-metadata">

**Author:** ![ms6676749](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/m/b4bc9f/32.png) [@ms6676749](https://community.mp3tag.de/u/ms6676749)\
**Post date:** [August 15, 2016, 3:44am UTC](https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177/3 "2016-08-15T03:44:57Z")

</div>

> [@ohrenkino](#):
>
> I think that this expression works:
> 
> $regexp(%title%,'^._feat. (._))',$1)

Yes, this works. I guess I didn't bracket my regexp with apostrophe's earlier. Thanks!

Anyways, in the meantime, I came up with an action that does a little bit of everything in taking GUEST ARTIST information from %title% and placing it in its own field while also formatting %title% to make it look uniform. I'm posting this here just for reference in case someone comes across this thread seeking similar answers:

```
[#0]
T=5
F=TITLE
1=$regexp(%title%,(^.*)(Ft\\\\.|ft\\\\.|feat\\\\.|featuring|Featuring|Feat\\\\. )(.*$),$1\\\\'('feat\\\\. $3\\\\')')

[#1]
T=2
F=TITLE
1=((
2=(
3=0|0

[#2]
T=2
F=TITLE
1=))
2=)
3=0|0

[#3]
T=2
F=TITLE
1=  
2= 
3=0|0

[#4]
T=7
F=%title%
1=%dummy% (feat. %GUEST ARTIST%)

[#5]
T=7
F=%title%
1=%dummy% (feat. %GUEST ARTIST%) (%dummy%)

[#6]
T=2
F=GUEST ARTIST
1=,
2=;
3=0|0

[#7]
T=2
F=GUEST ARTIST
1= & 
2=; 
3=0|0

[#8]
T=2
F=GUEST ARTIST
1=; Jr.
2=, Jr.
3=0|0

[#9]
T=16
F=GUEST ARTIST
1=;

```

---

<div class="post-metadata">

**Author:** ![system](https://community.mp3tag.de/uploads/default/original/2X/c/ce7035d426cb755a7916793326d23b465222a407.png) [@system](https://community.mp3tag.de/u/system)\
**Post date:** [February 9, 2026, 12:26pm UTC](https://community.mp3tag.de/t/problem-with-regexp-in-an-action/18177/4 "2026-02-09T12:26:22Z")

</div>

Closed on February 9, 2026, 12:26pm UTC