I see, you want to open PDFs in a Linux app instead of using the Chrome web browser on your Chromebook. In that case, you can associate PDF files with a Linux PDF viewer like `Evince`, `Okular`, or `Document Viewer`. Here's how you can do it:
1. **Find the Command:**
Determine the command that launches the PDF viewer you want to use. For example, if you want to use `Evince`, you can typically use the command `evince %f`.
2. **Open Thunar Preferences:**
Open Thunar, go to "Edit" in the menu bar, and select "Preferences."
3. **Go to the "Advanced" Tab:**
In the Thunar Preferences window, click on the "Advanced" tab.
4. **Configure Default Applications:**
Under "Default Applications," click on the "Add" button (or equivalent) to add a new entry.
5. **Add the Entry:**
- For PDF files:
- MIME Type: `application/pdf`
- Command: `evince %f`
Make sure to replace `evince` with the actual command of the PDF viewer you want to use if you're not using `Evince`.
6. **Save Changes:**
Click "Close" to save the changes.
7. **Test the Association:**
Try opening a PDF file in Thunar by double-clicking it. It should now open using the Linux PDF viewer you associated.
Remember to replace `evince` in the command with the appropriate command for your chosen PDF viewer. The `%f` placeholder is used to pass the file path to the command.
If you later decide to change the default application for a specific file type, you can return to the Thunar Preferences and modify the association or remove it altogether.