There are several ways to change your default applications on Ubuntu. Whether you’re changing the default application for a particular task, file type, or a system-level application like your default text editor, there’s a different place to go.
Unlike on Windows, applications won’t take over existing file extensions during the installation process — they’ll just appear as an option after you install them.
To set your default desktop applications for actions such as Web Browser, Email, or Video, open the System Settings window from the panel.
Select the Details icon in the System Settings window.
Select the Default Applications category and use the drop-down boxes to select a default application. Application will appear here after you’ve installed them – for example, you can install VLC and select it as your default video player from here.
From the Details control panel, you can also select your default applications for different types of removable media. By default, Ubuntu will ask you what application you want to use when you insert a removable media device. You can change this – for example, you can have Rhythmbox automatically open and play audio CDs when you insert them.
To set the default application for a specific file type, locate a file of that type in the file manager, right-click it, and select Properties.
Click the Open With tab and select the application you want to use for that file type. Use the Set as default button to make the application the default application.
Ubuntu uses the update-alternatives system it inherited from Debian to control default applications outside of the graphical desktop. For example, when you run a command that uses a terminal text editor, the command calls /usr/bin/editor. /usr/bin/editor isn’t an editor itself – it’s a symbolic link to an editor on your system. This link points to the nano text editor by default, but you can select a different default text editor with the update-alternatives command. If only one option is available for an alternative – for example, if you only have one Java virtual machine installed – it will be used as the default.
For example, let’s say you wanted to change the system’s default text editor. Run the following command in a terminal:
sudo update-alternatives –config editor
You’ll see a list of installed editors to choose from – type the number of the editor you want to use and press Enter.
To go through the choices for every alternative on your system, run the following command:
sudo update-alternatives –all
You’ll only see a prompt if multiple applications that could satisfy an alternative are installed on your system. To keep the default option for an alternative, just press Enter.