Install scim-unikey by entering the following commands in the terminal:
sudo apt update sudo apt install scim-unikey
Description:
Vietnamese Input Method Engine for SCIM using Unikey Engine
Smart Common Input Method (SCIM) is an input method (IM) platform. . Scim-Unikey is a Vietnamese input method for SCIM Use Unikey engine to process keyevent
Homepage: http://scim-unikey.googlecode.com/
Version: 0.3.1+debian-3.1ubuntu1
Section: universe/utils