You can easily reassign what application to open what file type on Ubuntu 17.10. For example, you might want to open every PNG picture with Shotwell rather than the default Image Viewer. To do so, per file type, do these following steps with 3 file type examples (PNG, MP4, TXT):
Example 1: For PNG Pictures
Suppose you want to open PNG always with Shotwell* instead of the default Image Viewer. To reassign it:
- Right-click a PNG picture > Properties > go to Open With tab.
- You see there the selected default app is "Image Viewer".
- Change the selection by selecting "Shotwell"
- Press Set as Default.
- Now every time you open PNG, it opens in Shotwell.
Going to 'Open With':
In the 'Open With':
*) Tip: Shotwell is very convenient if your daily work is to crop many pictures, because Shotwell can crop but Image Viewer cannot.
Example 2: For MP4 Videos
Suppose you want to open MP4 always with VLC instead of the default Video Player. To reassign it:
- Right-click a MP4 video > Properties > go to 'Open With' tab.
- You see there the selected default app is "Totem".
- Change the selection by selecting "VLC"
- Press Set as Default.
- The VLC is now at "Default Application" section.
- Now every time you play MP4 video, you use VLC.
Going to 'Open With' dialog:
In the 'Open With' dialog:
Example 3: For TXT Text File
Suppose you want to open TXT files always with Geany instead of Text Editor. Let's assume you have installed Geany. Then, to reassign it:
- Right-click a TXT file > Properties > go to 'Open With' tab.
- You see the default one is Text Editor.
- Select Geany.
- Press Set as Default.
- Now every time you open TXT, you use Geany.
Another Way, But Limited
If you want to reassign just the main applications (they are: web browser, mail client, calendar, audio and video player, and image viewer) then simply go to System Settings > Details > Default Applications > change what you want there. Remember, you cannot reassign TXT or PDF application there because the options are limited. The best way is by reassigning per file type like 3 examples above.
Revert to Defaults
To revert back your changes into each file type's default application, just do the same steps, but click "Reset" button at 'Open With' tab. You should see the 'Default Application:' section showing the default program.
