Ubuntu 16.04 LTS下CapsLock作Compose键时多字符组合失效求助

Hey there, let's dig into this Compose key problem you're hitting on Ubuntu 16.04 LTS—where CapsLock is set as your Compose key, but the Compose+'+j combination does nothing. I've dealt with similar quirky Compose behavior before, so here's what you can check and try:

• Confirm your Compose key mapping is correct
  First, make sure CapsLock is properly registered as the Compose key. Run this command in the terminal to verify:

  gsettings get org.gnome.desktop.input-sources xkb-options
  

  You should see ['compose:caps'] in the output. If not, set it with:

  gsettings set org.gnome.desktop.input-sources xkb-options "['compose:caps']"
  

  Log out and back in to apply the change fully—sometimes half-applied settings cause odd issues like this.

• Check the system Compose table entry
  The Compose+'+j combo is supposed to generate ǰ (a j with two diacritics: caron and acute). On Ubuntu 16.04, system Compose tables live in /usr/share/X11/locale/en_US.UTF-8/Compose (or your active locale's equivalent file). Open it and search for this line:

  <Multi_key> <apostrophe> <j> : "ǰ" U01F0
  

  If the line is missing, commented out, or has a typo, that's almost certainly the root cause. You can add it manually if needed, or copy the entry from a working locale's Compose file.

• Test with a different Compose key
  To rule out a CapsLock-specific quirk, temporarily switch your Compose key to Right Alt using:

  gsettings set org.gnome.desktop.input-sources xkb-options "['compose:ralt']"
  

  Try Right Alt+'+j—if it works, the issue is likely tied to how Unity/Xorg handles CapsLock as a Compose key on 16.04.

• Pinpoint whether it's Xorg or Unity
  If you're unsure which component is at fault, test the combo in a lightweight desktop environment (like Xfce, installable via sudo apt install xfce4). If it works there, the problem is Unity-specific. If it still fails, it's more likely an Xorg bug in the 16.04 release.

• Workaround: Custom user Compose file
  If none of the above fixes it, create a user-specific Compose override file. Make a ~/.XCompose file with this content:

  include "%L"
  <Multi_key> <apostrophe> <j> : "ǰ" U01F0
  

  This will force the combo to work for your account, overriding the system table. Log out and back in to activate it.

Quick note: Ubuntu 16.04 is end-of-life (since 2021), so official fixes for bugs like this aren't available. Upgrading to a newer LTS (like 22.04) would likely resolve this long-term if that's an option for you.

内容的提问来源于stack exchange，提问作者Ivan G.