How can I input Unicode characters in Kate and Konsole on Kubuntu 18.04?

Solution 1:

As you observed, many Unicode characters can be entered in gtk-based applications using Ctrl+Shift+u followed by a specific alphanumeric string but such an approach doesn't work at all in Kate or Konsole. This has been the case since 2005 at least.

One has to instead use a Compose key. To do that, open System Settings > Input Devices > Keyboard > Advanced. In there, scroll down to Position of Compose Key. Expand that by clicking on > and choose a convenient key. I chose Caps Lock. Be aware that you'll no longer have the normal function of that key or any other key you set as the Compose key:

Once that is done, create an empty (hidden) file called .XCompose in your home folder and add the following line:

include "/usr/share/X11/locale/en_US.UTF-8/Compose"

Save the file. Then, examine /usr/share/X11/locale/en_US.UTF-8/Compose for suitable code as shown in an answer to How to type unicode characters in KDE?.

Here's a few examples copied from the answer:

• Compose, v, C   →   Č
• Compose, ´, E   →   É
• Compose, _, u   →   ū
• Compose, ^, i   →   î

If you still find there are symbols that you can't generate in Kate or Konsole such as the one in your question, ሴ, a very, very, ugly workaround is to make a text file in a gtk text editor, generate all the missing symbols there, save the file and then copy/paste as needed into Kate or Konsole whenever you need them. That works just fine and saves the trouble of memorising a list of Unicode characters.