I had never before had to set up an alternate input method for myself. However, today, my wife asked me to help her do so.

An input method helps users type characters in other languages. Two popular input method frameworks are IBus and fcitx. In this example, I'll show how I got IBus working on a Debian-based distro.

1. Install IBus:

   apt install ibus
   

2. [Optional] Install additional input methods, for example:

   apt install ibus-cangjie ibus-zhuyin
   

   IBus appears to come with support for many western languages (French, German, Spanish, etc.) but not most non-Roman or non-Germanic lanuages, presumably because the libraries for these languages are probably much larger.

3. Configure IBus to enable the installed input methods by running

   ibus-setup
   

   This will allow the user to select the input methods they wish to switch between and will also enable a hotkey (for example, Ctrl+space) to quickly switch between them.

4. Enable IBus to be run at login:

   im-config -n ibus
   

   This sets IBus to run in your .xinputrc file. Presumably, this file is read by XOrg when starting to configure the input method. The contents of this file will probably be something like

   im_run ibus
   

   But I cannot verify this on my wife's machine right now because she is busy working.

5. Log out and log back in to ensure IBus is running. For some reason, I could not get it to work by just running ibus. Presumably, it is necessary to run it while XOrg is starting, not after it has already started.

At this point, it should work. Press the configured shortcut for switching keyboards and see if the input has changed. There should also be a tray icon that users can click to change the input method or configure settings.