I was ready to continue reading my book. Double-clicked and BAM! The not so great epdf-viewer popped up. Not this time fellow. So like every average linux man/woman/etc I decided to change the default application for pdf files. I alread had foxit-reader installed. So I knew it was oppening it via xdg-open. The xdg-open relies on the xdg-mime to query and determine the default application for a given file type. But there is a catch. I didn't know what flags to pass. So like my professor always said: "When in doubt, man it".

man xdg-mime

And there it was. xdg-mime default application mimetype(s). Only one teeny tiny problem. What is the mimetype here? Is it file extension? or what we web developers called the content-type? It's not application/pdf right? So if the epdf-viewer is oppening it, there should be a key/val somewhre. but where?


> xdg-mime query default image/png

So I have command is 100% doing some IO. So I decided to strace it.

> strace -e file xdg-mime query default image/png
newfstatat(AT_FDCWD, "/home/tur1ng/.config/mimeapps.list", {st_mode=S_IFREG|0644, st_size=2399, ...}, 0) = 0

Great. So a simple cat-greping should do the trick.

> cat ~/.config/mimeapps.list | grep pdf

Aha, I was right. To be honest the second I saw image/png I knew it was the same as the content-type. But regardless, I was right.

So let's xdg-mime it.

> xdg-mime default foxitreader.desktop application/pdf

Beautiful. I can now read my book in peace.

Turns out xdg-mime accepts another flag. Of course it does. xdg-mime query filetype filename and it will return the mimetype.

>  xdg-mime query filetype ./anything.pdf