&gt; xdg-open, which as it turns out opens text files in Firefox, even though light weight editors are present on the system.<p>It opens text files in Emacs here – did you configure your system to associate the text&#x2F;plain mimetype to Firefox? (The following mostly for anybody who is interested):<p><pre><code>  $ xdg-mime query filetype &lt;file&gt;
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will print the mimetype of &lt;file&gt;.<p><pre><code>  $ xdg-mime query default &lt;mimetype&gt;
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will print the default .desktop file associated to this mimetype, i.e. the application that is run if you do xdg-open. That application can be changed using<p><pre><code>  $ xdg-mime default &lt;.desktop&gt; &lt;mimetype&gt; [&lt;mimetype&gt;*]
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Maybe that particular distribution was misconfigured to have the default for text files be Firefox, but overall I don’t find the behaviour particularly surprising.