Preferred Applications
Since xfce4-settings 4.15.1 preferred applications have been moved from exo to xfce4-settings. Please refer to the xfce4-settings wiki page.
exo-open
A simple command line front-end to the Preferred Applications framework is included, called exo-open. You can use this utility to launch the preferred application for a certain category or open URLs with the default URL handler.
exo-open supports two operation modes. The first will simply launch the preferred application for a certain category, optionally passing a parameter. For example, to launch the command mutt in your set preferred Terminal Emulator, you would use:
exo-open --launch TerminalEmulator mutt
In order to open the preferred Web Browser with no additional parameters, the following command would be used:
exo-open --launch WebBrowser
The second mode supported by exo-open opens all parameters passed to it with the default URL handlers. Here URLs mean either fully qualified URLs (i.e. https://www.xfce.org/ or mailto:xfce4-dev@xfce.org), or local paths (i.e. ~/myfile.txt). For example, to open ~/file1.mp3 and ~/file2.txt in the set default applications, you would use the following command:
exo-open ~/file1.mp3 ~/file2.txt
To start composing an email to the xfce4-dev mailing list in the preferred mail reader application for instance, you can type:
exo-open mailto:xfce4-dev@xfce.org