How does calibre determine viewer to invoke on Debian?

oddhack · 01-13-2025, 09:23 AM

When I asked calibre running on Debian 12 to view a book in PDF form, it launches ebook-viewer instead of the PDF viewer configured in mime.types / mailcap. I am guessing this is because it's doing something involving XDG, since

xdg-mime query default application/pdf

returns

calibre-ebook-viewer.desktop

(and ebook-viewer is definitely not a PDF viewer). It is not clear to me where it's getting this association from, as I'm not even running an XDG-compliant WM (WindowMaker) and don't have any of the XDG environment variables set.

I'm drowning in XDG documentation at the moment trying to figure out what's going on, and it would be easier if someone in the forums happens to know what calibre is actually doing to determine this association (and even easier if there's some way to override the behavior globally in calibre, instead of right-clicking on the PDF and selecting a different application every time).

Failing that all I can think of is using xdg-settings to alter this, then look at the filesystem to see what files got updated as a result of doing that.

kovidgoyal · 01-13-2025, 10:05 AM

calibre doesnt determine it, Qt determines it and it used to use xdg-open, though I havent looked at its source code recently. My long standing recommendation on Linux is to just write your own xdg-open script, put it somewhere in PATH ahead of the system one, and free yourself from all that useless XDG baggage forever.

oddhack · 01-13-2025, 09:05 PM

Quote:

Originally Posted by kovidgoyal

calibre doesnt determine it, Qt determines it and it used to use xdg-open, though I havent looked at its source code recently. My long standing recommendation on Linux is to just write your own xdg-open script, put it somewhere in PATH ahead of the system one, and free yourself from all that useless XDG baggage forever.

Thanks! That's all I needed to move forward.

oddhack · 01-14-2025, 03:28 AM

Eventually sorted out that

$ xdg-mime default org.gnome.Evince.desktop application/pdf

fixes the problem, per https://wiki.archlinux.org/title/GNO...ocument_viewer . This appears to modify only $HOME/.config/mimeapps.list in my setup. And now calibre is opening PDFs in evince once again. A bit annoying that I will never know what random package I installed may have decided to replace this association, without asking.

01-13-2025, 09:23 AM	#1
oddhack Junior Member Posts: 3 Karma: 10 Join Date: Jan 2025 Device: none	How does calibre determine viewer to invoke on Debian? When I asked calibre running on Debian 12 to view a book in PDF form, it launches ebook-viewer instead of the PDF viewer configured in mime.types / mailcap. I am guessing this is because it's doing something involving XDG, since xdg-mime query default application/pdf returns calibre-ebook-viewer.desktop (and ebook-viewer is definitely not a PDF viewer). It is not clear to me where it's getting this association from, as I'm not even running an XDG-compliant WM (WindowMaker) and don't have any of the XDG environment variables set. I'm drowning in XDG documentation at the moment trying to figure out what's going on, and it would be easier if someone in the forums happens to know what calibre is actually doing to determine this association (and even easier if there's some way to override the behavior globally in calibre, instead of right-clicking on the PDF and selecting a different application every time). Failing that all I can think of is using xdg-settings to alter this, then look at the filesystem to see what files got updated as a result of doing that.

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01-13-2025, 10:05 AM	#2
kovidgoyal creator of calibre Posts: 45,311 Karma: 27111242 Join Date: Oct 2006 Location: Mumbai, India Device: Various	calibre doesnt determine it, Qt determines it and it used to use xdg-open, though I havent looked at its source code recently. My long standing recommendation on Linux is to just write your own xdg-open script, put it somewhere in PATH ahead of the system one, and free yourself from all that useless XDG baggage forever.

01-14-2025, 03:28 AM	#4
oddhack Junior Member Posts: 3 Karma: 10 Join Date: Jan 2025 Device: none	Eventually sorted out that $ xdg-mime default org.gnome.Evince.desktop application/pdf fixes the problem, per https://wiki.archlinux.org/title/GNO...ocument_viewer . This appears to modify only $HOME/.config/mimeapps.list in my setup. And now calibre is opening PDFs in evince once again. A bit annoying that I will never know what random package I installed may have decided to replace this association, without asking.

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