Linux Key Combinations

This explains how to type some special characters in Linux.

A much more thorough listing is to be found in Sander van Geloven’s Compose Key Sequences Reference Guide 2012 (Hellebaard, Utrecht).

It may be useful to understand something about the related concepts of character encoding, input method, and key code. See Character Encodings in Linux.

On my keyboard, the “right-Alt” key is the compose key. I had to set the compose key up myself, using System Settings → Keyboard.

To produce a character, hold down the compose with the key in the meta column below then type the key in the combo column below to get the result. The main key must be pressed shortly after pressing the compose key—otherwise it will time out.

When shift is required with meta, hold it down before holding down compose.

Some other useful commands in this connexion: dump keys, show key.

This list is not exhaustive. I’ve only listed the ones that seemed of most direct use to me. There are, for examples, whole other sets for entering special letters and symbols in a Cyrillic or Greek environment.

On my system, the key combinations for UTF-8 encoding for U.S. English keyboard is in /usr/share/X11/locale/en_US.UTF-8/Compose/.

Note that for some characters may be produced by several different key combinations. Use the one that's easiest to remember.

Some combinations use three keystrokes. For these, the compose key should be held down only while the first, meta, key is pressed.

General Unicode entry

To input a Unicode character code, such as “U+25A0” for “BLACK SQUARE”, ■, hold down CTRL+SHIFT+u, then type in the code 25A0, and hit return.