For gnome/budgie:
- In the Settings, look for Region & Languages and in here click on the + symbol under the Input Sources.
- Click on the + icon
- Click on ⠇icon
- Scroll down, select English(India)
- Select English (India, with rupee)
- Change keyboard layout using (super+space) key
- Reorder in region&language
Alternatively try (right-alt+4) key combination
For plasma:
- Navigate to Application Launcher -> System Settings -> Hardware -> Input Devices -> Keyboard -> Layouts
- Check the box “Configure Layouts” and click “Add”
- Choose “Indian” from Layout drop-down box and “English (India, rupee sign”) from Variant drop-down box.
- Choose it and click “Move up” to make it as default keyboard layout.
- Then, click Advanced and click “Key to choose the 3rd level” and choose a key of your choice to apply for rupee symbol. I have chosen “Any Alt” key. Finally, click “Apply”
Alternatively try (right-alt+4) key combination