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I know that there are extensive, "proper" methods for installing Firefox plugins. However, I would like to know where the folder is for linking shared-object (.so) files, such as and so that I can install plugins the "old-fashioned" way. In Firefox 21, I would have put it in ~/.mozilla/firefox/*[profile name].default/browser/plugins but that folder is no longer there. It keeps jumping around as Firefox changes. In about:plugins I still see all the plugins that I would have put there.

Can anyone tell me where the folder is? I already checked the folders in /usr/lib/firefox and /usr/lib/mozilla.

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up vote 32 down vote accepted

Acording to the Firefox developer documentation plugins live here:

  • Directory pointed to by MOZ_PLUGIN_PATH environment variable
  • ~/.mozilla/plugins
  • /usr/lib/mozilla/plugins (on non-Ubuntu 64-bit systems, /usr/lib64/mozilla/plugins might be used instead)
  • Plug-ins within toolkit bundles
  • [Profile directory]/plugins, where [Profile directory] is a user profile directory

I can reproduce the above on my system.

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Mine is 64-bit system but i found out that it is at /usr/lib/mozilla/plugins. Also it is a good idea to have a look at about:plugins tab that may give a hint. – Fredrick Gauss Jun 10 '15 at 5:49
Fredrick Gauss's comment holds good for 14.04 too. – learner Aug 9 '15 at 3:38
@learner, thanks. The info is directly from the Firefox documentation. Ubuntu puts 64bit libs in /usr/lib and 32bit libs in /usr/lib32 instead of having a lib64 directory. So I changed the answer a little to reflect that. – mniess Aug 11 '15 at 13:31

I am on KDE 32bit 14.04 version. Firefox is already installed.

user Richard got negative reputation by telling us the correct path:


If you are proper linux user, it's no problem to move file to this directory as root user!

Youtube works after dat!

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Users should place plugins in /usr/lib/firefox-addons/plugins as root.

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Users should do nothing as root. – mniess Nov 29 '13 at 23:02
This is only in the case you want a certain plugin to be automatically installed in all new user profiles. As a single user, you shouldn't install anything at all in this directory. – darent Nov 29 '13 at 23:18
@darent Where should we install the plugin then? – iamcreasy Dec 22 '14 at 10:15
@iamcreasy see the answer by user mnies – Richard Dec 22 '14 at 10:51

As a new Ubuntu user, I've been suggested to use the path mentioned by the about:plugins firefox command. In my case, it's pointing to /usr/lib/mozilla/plugins/.

Just mentioning here as I haven't seen this being mentioned. In case the approach isn't valid / reliable, I'd like to know why.

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Umm.. The accepted answer mentions /usr/lib/mozilla/plugins, and the question itself mentions about:plugins. – muru Dec 26 '15 at 17:54
Yeah, my takeout is that, regardless of version, we should be using what's stated @ about:plugins (which was already known by OP, but - I believe - he wasn't sure if that path was the de facto path to be used or not). – Tiago Cardoso Dec 26 '15 at 18:05
OK.. You should cite the source where you got this suggestion. – muru Dec 26 '15 at 18:06

I'm using Ubuntu 14.04 it is

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It differs from user to user... Better to write unique_key instead of e9k6f7k9 – Fabby Jan 6 at 23:21
-1 This is the extensions or add-ons directory, not the plug-ins directory. – David Foerster Jan 7 at 11:50

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