How to set a Compose Key in Ubuntu 18.04

Solution 1:

You may use (GNOME) Tweaks to set the option.

First install Tweaks by running

sudo apt install gnome-tweaks

(or sudo apt install gnome-tweak-tool).

Alternatively, for those who prefer the GUI:

1. launch the Ubuntu Software application.

2. search for "gnome tweaks".

3. install.

Then launch Tweaks and go to "Keyboard & Mouse" section. The "Compose Key" options is disabled by default. Click on the "Disabled" button.

Then a window will pop up. Toggle the switch at the top on and then you'll be select the compose key

Solution 2:

To expand upon what @pomsky detailed in their answer, the official documentation covers the two solutions available.

One is through installing Gnome Tweak Tool via the terminal like so: sudo apt install gnome-tweak-tool

And the other is typing the Unicode character's code point. To do this, press Ctrl+Shift+U, release all keys (you'll see an underlined u), type the code point desired, and then press Space or Enter to complete.

For example, a common one I use is referred to as “Smart Quotes” which are U+201C & U+201D respectively. So you would type 201C or 201D after releasing the initial keys, and complete the process with Space or Enter.

Solution 3:

The dconf setting that worked for my GNOME 3.28.2 is

/org/gnome/desktop/input-sources/xkb-options

To set the Scroll Lock as the compose key, the value should be

['compose:sclk']

See the gnome-tweaks source code for other potential values.

That means you can run a command like this:

dconf write /org/gnome/desktop/input-sources/xkb-options "['compose:sclk']"

Solution 4:

Issue man xkeyboard-config and look for the compose options (shortcut: enter /compose:). You will find

compose:ralt          Right Alt                  
compose:lwin          Left Win                   
compose:lwin-altgr    3rd level of Left Win      
compose:rwin          Right Win                  
compose:rwin-altgr    3rd level of Right Win     
compose:menu          Menu                       
compose:menu-altgr    3rd level of Menu          
compose:lctrl         Left Ctrl                  
compose:lctrl-altgr   3rd level of Left Ctrl     
compose:rctrl         Right Ctrl                 
compose:rctrl-altgr   3rd level of Right Ctrl    
compose:caps          Caps Lock                  
compose:caps-altgr    3rd level of Caps Lock     
compose:102           <Less/Greater>             
compose:102-altgr     3rd level of <Less/Greater>
compose:paus          Pause                      
compose:prsc          PrtSc                      
compose:sclk          Scroll Lock                

Let us say you want to pick Pause as the compose key. Just issue

setxkbmap -option compose:paus

To make it reboot-persistent, open /etc/default/keyboard with your favorite editor.

sudo nano /etc/default/keyboard

and to the line XKBOPTIONS add compose:paus. If you had other options already, separate them with commas. For example:

XKBOPTIONS="terminate:ctrl_alt_bksp,compose:paus"

Multiple compose keys can be used simultaneously.