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On my Gentoo box running without a desktop environment, every time I try to open a file the system tries to open it with Firefox. I understand that without a desktop environment "open file" cannot function correctly, but why is everything opened with Firefox? If I want to, can I change it to something else?

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How are you trying to open the file? Under most unices, this is a per-application concept, not a generic OS concept. – Gilles Dec 21 '10 at 20:31
@Gilles I tried in various ways: double-clicking from pcmanfm, clicking from the downloaded section of chromium, executing xdg-open. Firefox always comes up. – phunehehe Dec 22 '10 at 1:17
Chromium and xdg-open both use the FreeDesktop database. I don't know about pcmanfm. – Gilles Dec 22 '10 at 18:53
up vote 5 down vote accepted

Usually this information is handled in 2 places:

  • Application .desktop files advertise what program can open
  • MIME database which specifies what application should be used to open file with specific MIME

The MIME database can be customized by editing .local/share/applications/mimeapps.list and .local/share/applications/mimeinfo.cache. The tool which allows to edit it is xdg-mime from x11-misc/xdg-utils. Please beware that man states it can be used only from inside desktop session.

Edit Please note that some applications, like Firefox, do not respect the MIME database settings.

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That's the FreeDesktop MIME database. Other applications might use the system database (/etc/mailcap, ~/.mailcap); Firefox has its own proprietary database. – Gilles Dec 22 '10 at 18:54
I know it under name of MIME database (sounds completely different then FreeDesktop MIME database). As Freedesktop is set of standards for X desktop environments I don't think I was wrong to present is as standard - and I did mentioned not all apps respect it. – Maciej Piechotka Dec 22 '10 at 19:00
Thanks for the right direction. The default application list is at .local/share/applications/defaults.list (which is also what xdg-mime edits). – phunehehe Feb 15 '11 at 15:35

The command file -i <filename> might be useful for the cases when one does not know the specific mime type of a particular file. Once established it may be used as an input to xdg-mime utility to set the default open command.

dev-perl/File-MimeInfo ebuild constains mimeopen utility. It is a wrapper around the mentioned above commands.

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