I do not know where to ask this.

When I type help, I get "help: Help is being displayed in xdg-open." Which is normal I suppose, but the problem is it opens up in Todoist application, which is an AppImage application.

I have searched around and can't find a good starting point on how to fix this.


  • 1
    You have to find out the mimetype of the help file with xdg-mime query filetype helpfile and then set the desired app with xdg-mime default app.desktop mimetype
    – Harry
    Jul 28, 2022 at 19:43
  • Who would ever think in my case that text/html was a wrong direction of my troubleshooting because of another obscure type application/xhtml+xml interfering to type detection! Lo and behold: "xdg-mime query filetype q.html" gives "application/xhtml+xml" while "file --mime-type q.html" gives "q.html: text/html" WTF going on in this mime-world-tm?? I couldn't resolve this issue for few last years until hit on this comment above!
    – Van Jone
    Jan 31 at 23:36

1 Answer 1


As @Harry pointed out, first determine the mime type of the file in question:

  1. file --mime-type $somefile

You can then check what sources a querried by xdg-open regarding the application to run the corresponding file type:

  1. XDG_UTILS_DEBUG_LEVEL=2 xdg-mime query default $type

If you're not happy with the default application for a type, you can override it:

  1. (Optional) Edit ~/.config/mimeapps.list

See the Arch Wiki.

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