Installing Unikey for Vietnamese typing on Ubuntu is not as straightforward as on Windows. If you're unsure how to do it, follow this guide.

1. Installing Unikey package via Terminal
Step 1: Right-click on the screen and select Open Terminal.

Step 2: Enter the following command and press Enter:
sudo add-apt-repository ppa:ubuntu-vn/ppa

Next, input your password and press Enter. After entering the password, press Enter again.

Step 3: Enter the following command and press Enter.
sudo apt-get update

Step 4: Proceed with the next command.
sudo apt-get install ibus-unikey

Step 5: Restart ibus with the following command.
ibus restart

2. Setting up Unikey on Ubuntu
2.1. For older versions of Ubuntu (17.10 and below)
Step 1: Right-click on the desktop => Open Terminal.

Step 2: Enter the following command and press Enter:
ibus-setup

A new window will appear, click on Input Method (1) => Add (2).

Step 3: Scroll down to find and click on Vietnamese.

Select Unikey (1) => Add (2).

Afterward, close the installation and restart your computer. If the Unikey option doesn't appear in the system tray, follow these steps.
Step 4: Click on Power (1) => System Settings… (2).

Step 5: Click on the Text Entry section.

Next, click on the + symbol.

Step 6: Locate the line Vietnamese (Unikey) (iBus) (1) => Add (2).

At this point, your Unikey input method has been added to the list. Check the box for Show current input source in the menu bar to display Unikey on the menu bar.

Step 7: Now, you will see Unikey appear on the menu bar. Try typing Vietnamese with this tool to ensure there are no errors.

2.2. For Ubuntu version 18 and above
Step 1: Click on the triangle button (1) next to Power => Settings (2).

Step 2: Click on the Region & Language (1) section => click on the + (2) symbol in Input Sources.

Next, click on Vietnamese.

Step 3: Click on Vietnamese (Unikey) (1) => Add (2).

Step 4: To use the Vietnamese typing tool Unikey, simply click on Input (1) => Vietnamese (Unikey) (2).

With detailed and quick instructions in this article, you can easily install Unikey on Ubuntu. Wishing you success!