You can type characters beyond those on your keyboard in most X programs that use keyboard input (terminal emulators, web browsers inside text areas, etc.).  This is done with libX11's [[DebianMan:XCompose|Compose(5)]] feature.  A multi-key input sequence is mapped to a character; for example, <Compose> <e> <'> generates the character '''é'''.

Once you have set this up, you can type accented letters (é å ù), other European characters (ç ñ), Greek letters (α β), or whatever else you choose to configure.

== Standard way ==
The first step is to define a '''Compose''' key, also known as a '''Multi_key''' key.  Many people choose to use one of the "Windows" keys, or the "Menu" key, or one of the "Alt" keys.  Whichever key you choose, run an [[DebianMan:xmodmap]] command to assign it a new meaning.  For example, to use the Left Windows key:

{{{
xmodmap -e "keysym Super_L = Multi_key"
}}}

Make sure this command is executed whenever you login to X, for example by placing it in your [[Xsession|~/.xsessionrc]] file.  Other files may be used, depending on how you start X, which Desktop Environment you use, and so on.
Once you have defined a Compose key, you should immediately be able to type the basic accented letters in a terminal emulator.  The full list of default compose sequences may be found in '''/usr/share/X11/locale/en_US.UTF-8/Compose''' for reference.  If you're happy with these, you may stop here.

The second step is to configure your own custom compose sequences.  To do this, create a file named '''~/.XCompose''' and make sure it has '''include "%L"''' at the top of it, to bring in the default sequences.  After that, you may put whatever you like.  For example,

{{{
include "%L"

<Multi_key> <g> <a> : "α"
<Multi_key> <g> <b> : "β"
<Multi_key> <g> <g> : "γ"
}}}

This file is read by libX11 whenever a new X program is started.  So, your existing terminals won't be able to type these new characters, but any new terminals you launch will.

There is a bit of a chicken-and-egg issue with getting the desired characters into the .XCompose file in the first place.  The easiest way is to find a web page that has the character(s) you want, and copy and paste them into your .XCompose definitions.

== KDE Way ==
There is a simple GUI config to set a Compose key in KDE.

{{{
systemsettings/hardware/keyboard/advanced
Enable config keyboard options
Disable annoying caps-lock
Set position of Compose key to caps-lock
}}}
 
The list of all the codes is in /usr/share/X11/locale/en_US.UTF-8/Compose - more bits under other specific locale.alias..
 ( Need to create a list of commonly used codes here -- 88 - ∞ , +- - ±  , oo - ° , .. top of file is fairly useful )

== Also see ==
intl AltGr dead keys - can be used in combination with Compose-key. 

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CategoryDesktop