Calibre ebook-meta can't empty metadata

[Budfudder]

I've been using ebook-meta to change the metadata on my .mobi files, and I'm trying to empty as many of the metadata slots as I can. So far I've discovered the following parameters to empty slots:

--tags=""
--publisher=" "
--comments=" "

My first question is why does --publisher=" " empty the publisher slot, rather than --publisher=""? To empty the tags slot you use --tags="" - why not the same for the publisher and comments slots?

My second question is around the Book Producer slot. I can't empty this - I can't even change its content, no matter what I do. I've tried --book-producer="", --book-producer=" " and even --book-producer="test", but it remains the same no matter what. Here's sample output:

X:\Personal\eBooks>ebook-meta esop.mobi --book-producer=""
Original metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

Changed metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

X:\Personal\eBooks>ebook-meta esop.mobi --book-producer=" "
Original metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

Changed metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

X:\Personal\eBooks>ebook-meta esop.mobi --book-producer="test"
Original metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

Changed metadata::
        Title               : Aesop's Fables
        Author(s)           : Aesop
        Book Producer       : calibre (0.7.16) [http://calibre-ebook.com]
        Tags                :
        Published           : 0101-01-01T00:00:00+00:00
        Identifiers         : isbn:9781593080624
        Comments            :

I've tried this with an old version of Calibre (0.8.something), 0.9.5 and the latest, 0.9.22. It seems to not work on any of them. Or am I doing something wrong?

Thanks for any help.

[Budfudder]

Further to this, how can I empty the Languages metadata slot? I've done a bit of testing and from what I can see:

if the existing value of the Languages slot is "en", then --language=" " will empty the slot.

But if the existing value of the Languages slot is "eng", then it can't be changed at all - neither --language=" ", nor --language="" nor --language="en" will change it from "eng".

[theducks]

It won't work because you are trying to make an invalid entry.
Go learn about Language codes

[Budfudder]

Originally Posted by theducks

It won't work because you are trying to make an invalid entry.
Go learn about Language codes

Thanks so much for helping not in the slightest and being rude as well.

[jgaiser]

Originally Posted by Budfudder

Thanks so much for helping not in the slightest and being rude as well.

Looked pretty helpful to me. You need to go find out about Language codes, because what you're trying to do is illegal.

And I suspect you're not going to be able to change Book Producer, because it's built into calibre *because* it's the Book Producer.

[DoctorOhh]

Originally Posted by Budfudder

Further to this, how can I empty the Languages metadata slot? I've done a bit of testing and from what I can see:

if the existing value of the Languages slot is "en", then --language=" " will empty the slot.

But if the existing value of the Languages slot is "eng", then it can't be changed at all - neither --language=" ", nor --language="" nor --language="en" will change it from "eng".

Good question, you might want to submit a bug report and see what Kovid says.

In reference to the Book Producer slot, calibre is in fact the book producer so this might be a choice by Kovid. You can ask in your bug report but I suspect if you want to clear that field you'll have to do it in a 3rd party app like Sigil.

[Budfudder]

Originally Posted by jgaiser

Looked pretty helpful to me. You need to go find out about Language codes, because what you're trying to do is illegal.
And I suspect you're not going to be able to change Book Producer, because it's built into calibre *because* it's the Book Producer.

Thanks for this - that had honestly never occurred to me. It's strange that there's an option to do it when it appears you can't do it.

[Budfudder]

Originally Posted by DoctorOhh

Good question, you might want to submit a bug report and see what Kovid says.

In reference to the Book Producer slot, calibre is in fact the book producer so this might be a choice by Kovid. You can ask in your bug report but I suspect if you want to clear that field you'll have to do it in a 3rd party app like Sigil.

Thanks a lot, I wasn't aware there was a bug reporting mechanism. I'll use it.