Chinese learners or speakers may sometimes want to write out the romanisation for certain chinese characters complete with accents indicating the different tones. For example:
你好 [nǐhǎo]
This is possible using the Ibus input framework that comes with Ubuntu. The support for pinyin romanisation is provided in the ibus-m17n package. This must first be installed.
sudo apt-get install ibus-m17n
Once installed, restart Ibus and add the input method in the menu as in the screenshot below.
You should now be able to activate the input method. Simply type the pinyin for a character preceded by the tone number (ranging from 1 to 4).
