Changing of Keyboard Mappings with xmodmap



When running a Linux system in its graphical mode, keyboard mappings can be changed by using xmodmap.
Each key on the keyboard has a „keycode“ which can be found out by looking at the output of
xmodmap -pke > current-keyboard
or by running
for trying out the keys.

I am using a modified German keyboard, but off course the ideas can be adapted to any setup.

Given setting as a Basis

You can start with any keyboard, for example with the German keyboard with no dead keys, which is often useful as a starting point. I prefer to modify it a little bit. This allows me to support more languages like Swedish, Norwegian, Danish, Dutch, Spanish and Esperanto. Russian is an issue that I will address in another article. On the other hand it is a good idea to have secondary positions for some symbols that are on keys that might be missing on some physical layouts, like „<", "|" and ">“ on the German keyboard, whose key is just not present in the American keyboard. The third idea is to have two Altgr-keys, because many important symbols are just accessible in conjunction with Altgr and thus easier if there are two Altgr-keys like there are two Shift-keys.

Special characters for Esperanto

For Esperanto (Esperanto explained in Esperanto) the latin alphabet with its 26 letters is needed, even though some of them are never used. And on top of that the following letters are needed as well:
ĉ Ĉ ĝ Ĝ ĵ Ĵ ĥ Ĥ ŝ Ŝ ŭ Ŭ
Unfortunately they have not reused the letters commonly used in Slavic languages and present on many international setups:
č Č ž Ž š Š
but Unicode covers it all and as long as the keyboard does not need to support Slavic or Baltic or Sami languages simultaneously with Esperanto, things should be fine.

A reasonable approach is tu put these symbols on Altgr-C, Altgr-G, Altgr-J, Altgr-H, Altgr-S and Altgr-U.

This can be achieved easily:
Create a file

xmodmap -pke > .xmodmap-ori

And a script $HOME/bin/orikb:

xmodmap $HOME/.xmodmap-ori

Look up where the letters S, G, H J C and U are positioned on the keyboard in the xmodmap-ori-file.
Now create a file
using the following command

egrep 'keycode *[0-9]+ *= *[SsGgCcJjHhUu] ' < .xmodmap-ori

and edit it. Leave the part keycode = intact and change it to something like this:

keycode 39 = s S s S scircumflex Scircumflex
keycode 42 = g G g G gcircumflex Gcircumflex
keycode 43 = h H h H hcircumflex Hcircumflex
keycode 44 = j J j J jcircumflex Jcircumflex
keycode 54 = c C c C ccircumflex Ccircumflex
keycode 30 = u U u U ubreve Ubreve

The numbers between "keycode" and "=" could be different on your machine, but the rest should be like that.

Now create two scripts

xmodmap $HOME/.xmodmap-esperanto


xmodmap $HOME/.xmodmap-ori


Do not forgot to do the

chmod +x $HOME/bin/eokb $HOME/bin/orikb

for your scripts... 🙂

Now you can use eokb for enabling the Esperanto keys and orikb to return to your original setting.
The Esperanto keys will be accessible by using Altgr and the Latin letter they are derived from.

Other language specific characters

In a similar way you can have other characters
å and Å on the A,
ë and Ë on the E
ï and Ï on the I
ø and Ø on the O
æ and Æ on the Ä
ÿ and Ÿ on the Y
ñ and Ñ on the N
< on the , > on the .
| on the -

This allows to write a lot of languages. See what works for you...

Remaining Issues

For Russian I have bought a physical Cyrillic keyboard and I am using it with the setup that is printed on the keys. I might write about this another time.

Generally I like to have two Altgr keys and I can very well live without a windows key. I might write about this another time as well.

Btw. this article has been written for Linux, but it works perfectly well with any other Unix-like system, as long as X11 is used, just think of Aix, HPUX, BSD, Solaris and likewise systems. But Linux is by far the most common unix like desktop system these days.

Here is another approach:

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Tastaturbelegung mit xmodmap ändern (Linux/X11)



Wenn ein Linuxsystem im grafischen Modus läuft, kann man die Tastaturbelegung mittels xmodmap ändern.
Jede Taste hat einen sogenannten „keycode“, den man leicht ermitteln kann, indem man sich die jetzige Belegung mittels
xmodmap -pke > current-keyboard
ausgeben lässt oder mit
die Tasten ausprobiert. Ich benutze gerne eine deutsche Tastatur und tue das unabhängig davon, was auf den Tasten so aufgedruckt ist. In der Schweiz ist leider eine andere Belegung üblich, die minimale Abweichungen aufweist. Angeblich (inoffiziell) um die Schweizer Tastaturhersteller zu schützen, weil man vergass, dass asiatische Hersteller diese Hürde mühelos überspringen können. Ageblich (offiziell) um einen Kompromiss für die verschiedenen Sprachregionen der Schweiz zu schaffen und die Unterschiede minimal zu halten. Die Schweizer Tastatur ist aber unpraktisch, weil das „ß“ und die großen Umlaute fehlen.

Vorgegebene Einstellung als Basis

Nun kann man unter Linux eine Deutsche Tastatur mit „no dead keys“ wählen, was normalerweise sinnvoll ist. Oder sagen wir eine sinnvolle Ausgangsbasis. Ich finde es aber praktisch, diese noch etwas zu modifizieren. Einerseits können so mehr Sprachen unterstützt werden, wobei für mich die skandinavischen Sprachen, Spanisch, Russisch und Esperanto im Moment am interessantesten sind. Andererseits finde ich es praktisch, die Zeichen, die auf Tasten liegen, die bei manchen physikalischen Layouts fehlen, z.B. die drei Zeichen „<", "|", ">„, noch zusätzlich woanders hin zu legen, damit man sie auch dann noch hat. Drittens finde ich es schön, wenn man zwei Altgr-Tasten hat, weil viele wichtige Zeichen nur über Altgr erreichbar sind und sich besser greifen lassen, wenn es ein rechtes und linkes Altgr gibt.

Zeichen für Esperanto

Für Esperanto (Esperanto auf Esperanto erklärt) braucht man das übliche lateinische Alphabet mit 26 Buchstaben, wovon einige allerdings nicht verwendet werden, und die folgenden zusätzlichen Buchstaben:
ĉ Ĉ ĝ Ĝ ĵ Ĵ ĥ Ĥ ŝ Ŝ ŭ Ŭ
Leider hat man sich nicht an die in einigen slawischen Sprachen verwendeten zusätzliche Buchstaben
č Č ž Ž š Š
gehalten, aber solange man nicht außerdem slawische oder baltische Sprachen mit lateinischer Schrift parallel verwendet, ist das kein Problem.

Die sinnvollste Lösung scheint mir, die jeweiligen Zeichen auf Altgr-C, Altgr-G, Altgr-J, Altgr-H, Altgr-S und Altgr-U zu legen.

Das lässt sich recht einfach erreichen:
Man legt eine Datei

xmodmap -pke > .xmodmap-ori

Und ein Skript $HOME/bin/orikb:

xmodmap $HOME/.xmodmap-ori

Man legt danach eine Datei
an, in die man die folgenden Zeilen einträgt:

keycode 39 = s S s S scircumflex Scircumflex
keycode 42 = g G g G gcircumflex Gcircumflex
keycode 43 = h H h H hcircumflex Hcircumflex
keycode 44 = j J j J jcircumflex Jcircumflex
keycode 54 = c C c C ccircumflex Ccircumflex
keycode 30 = u U u U ubreve Ubreve

Und ein script in

xmodmap $HOME/.xmodmap-esperanto

Natürlich chmod +x für die Skripte nicht vergessen… 🙂

Nun kann man mittels eokb die Esperanto-Zeichen auf die Tastatur bekommen und mittels orikb den Originalzustand wiederherstellen.

Andere sprachspezifische Sonderzeichen

Auf ähnliche Weise lassen sich natürlich auch andere Zeichen auf die Tastatur bringen. Ich habe z.B. noch
å und Å auf dem A,
ë und Ë auf dem E
ï und Ï auf dem I
ø und Ø auf dem O
æ und Æ auf dem Ä
ÿ und Ÿ auf dem Y
ñ und Ñ auf dem N
< auf dem , > auf dem .
| auf dem –

Damit lassen sich die skandinavischen Sprachen, Spanisch und Esperanto schreiben.
Manchen Tastaturen fehlt die Taste <>| links neben dem Y zugunsten einer größeren Shift-Taste. Deshalb habe ich mir <>| zusätzlich noch auf Altgr-, , Altgr-. und Altgr– gelegt.

Ausblick für weitere Artikel zum Thema

Für Russisch habe ich mir eine kyrillische Tastatur gekauft und benutze die Belegung wie sie aufgedruckt ist.

Generell stört es mich, dass man so häufige Zeichen wie []{}\ nicht so gut erreichen kann und so habe ich jeweils Altgr rechts und links verfügbar gemacht…

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Java: Using Enums for Singletons

This singleton pattern is not really a big deal, but overused because it gives us the coolness of knowing about design patters without learning too much stuff for that… It does have its uses in some programming languages, while more or less implicit or obsolete in others, depending on the point of view.

I have already discussed the generalization of the singleton.
Actually it can be seen that the enum of Java and of languages who do something like Java’s enum in a similar way can be used as a way to build a singleton by just limiting it to one instance. Having been skeptical about this as an abuse of enums that might confuse people who read this I would now suggest to embrace this as a possible and useful way to write singletons and to be familiar with it when reading other people’s code or even to use it when writing code.

The enum way to write a singleton is the most elegant way in Java, because it uses least boiler plate code and includes some benefits that are usually ignored, especially when it comes to serialization that has to be addressed in singletons quite often, but is quite often ignored, resulting in multiple instances of the „singleton“ to float around…

So here we go:

enum Singleton  {

    private long count;

    private Singleton() {
        count = 0;

    public synchronized long nextValue() {
        return count++;


  • For real programs it would be important to check if long is sufficient or BigInteger is needed.
  • For real programs using an AtomicLong could be a better way than using synchronized.

Some links:

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Automation and its Limits

What we do in IT is programming and implementing and maintaining automatism. The general usefulness is not really challenged these days, but it was quite a big deal a few decades ago.
Many routine tasks can be done more efficiently and more reliably or become feasible at all with IT…

Just think of getting money from your bank account. Banks typically offer the possibility to do that at the bank counter without extra charges or any questions. But such a trivial operation can be done at the ATM, even while the counter is closed and I guess it is quite uncommon to go to the bank counter for that. There are more complex issues in banking that do require human interaction and they can be addressed with a human.

Buying a railroad ticket can be as trivial as getting money from the ATM, if the software of the ticket vending machine is really good, the tariff system is somewhat transparent, understandable and simple or at least the complexities can be covered well by the software. Most tickets are bought from the ticket vending machine, but the human at the ticket office in the railroad station is still important for more complex tickets that are not covered at all by the machine or that are too complex to buy there. It is interesting to see what can work and what not, maybe in another article in the future…

Phone lines are more and more answered by a machine, which has been given a beautiful voice by a human speaker… „For ABC press 1, for DEF press 2,….“ and so on. That works well for the trivial and most common cases. No matter how good the software is, usually at some point a limit is reached and we do want to find a human. I wanted to find out if there is a packaging service at some airport. It was possible to call, but there was no possibility at all or at least not within one hour of trying, to get to a human through these menus. So in the end the question remained unanswered. For the railroad ticket this can be an issue, if a more complex ticket is needed in a minor railroad station, but that can be solved nicely by providing a phone number (with real humans in the call center) that can be called and getting the ticket printed in ticket vending machine. This is possible in Germany and quite useful and basically covering most needs, even if talking with a real person is maybe nicer than a phone call with a dying battery… In Switzerland the ticket vending machines have a VOIP connection to the call center, so you do not even need to use the phone, but I think they are constrained to what can be done on the ticket vending machine GUI, so it does not help to solve the more difficult cases… Maybe in the future as well.

More delicate issues are the nanosecond trading. Trading (they do not like to call it gambling) on the stock exchange, with foreign currencies and all kinds of derivatives is done by algorithms automatically. Using software that is faulty, using the same software in many places, more or less. And also the risk management is done like that. It could be seen positive, because some traders tend to lose the sense of reasonable risk and machines kind of eliminate the emotions that can be counter productive in trading. But the risk takers are still there, setting out more automated trading systems… Will these systems one day create the real stock market crash by running into weird directions because of having the same software bug or because a situation not anticipated when the software was programmed occurs? Is it good to take such high risks without human control? Or it is even more delicate, if algorithms decide who is a terrorist and send drones, off course without a court order…

An issue that is mentioned quite a lot these days is motor vehicles operated automatically. While I do question the excessive use of cars of our time, I do think that that is an improvement, because human drivers are not very good and too risky. For rail transport this is much easier to achieve and many modern subway system operate automatically without any known problems.

We should always ask the question, does this IT solution and the automation it provides serve the humans and provide an advantage. That is the stuff we should build and operate.

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MS-Windows-Encodings with CMD: Bug or Feature?


Whoever is working with MS-Windows, should know these black windows with CMD running in them, even though they are not really popular. The Unix and Linux guys hate them, because they are really primitive compared to their shells. Windows guys like to work graphically. Or they prefer powershell or bash with cygwin. Linux and Unix have the equivalent of these windows, but usually they are white. Being able to configure the colors on both systems in any way this is of no relevance.

NT-based MS-Windows systems (NT 3.x, 4.x, 2000, XP, Vista, 7, 8, 10) have several subsystems and programs are running in them, for example Win64, Win32 (or Wow64 on 64-bit-systems), Win16, cygwin (if installed), DOS… Because programs for the DOS subsystem are typically started in a CMD window, and because some of the DOS commands have equally named and similarly operating pendents in the CMD window, the CMD window is sometimes called DOS-window, which is just incorrect. Actually this black window comes into existence in many situations. Whenever a program is started that has input or output (stdin, stdout, stderr), a black window is provided aroudn, if no redirection is in place. This applies for CMD. Under Linux (and Unix) with X11 it is the other way round. You start the program that provides the window and it automatically starts the default shell within that window, unless something else is stated.

Now I recommend an experiment. You just need an MS-Windows installation with any graphical editor like emacs, gvim, ultraedit, textpad, scite, or even notepad. And a cmd-window.

  • Please type these commands, do not use copy/paste
  • In the cmd-window cd into a directory you may write in.
  • echo "xäöüx" > filec.txt. Yes, there are ways to type these letters even with an American keyboard. 🙂
  • Open the file with a graphical editor. How do the Umlauts look?
  • Use the editor to create a second file in the same directory with contents like this: yäöüy.
  • view it in CMD:
  • type fileg.txt
  • How do the Umlauts look?

It is a feature or bug, that all common MS-Windows versions are putting the umlauts to different positions then the graphical editors. If you know how to fix this, let me know.

What has happened? In the early 80es MS-DOS came into existence. By that time standards for character encoding were not very good. Only ASCII or ISO-646-IRV existed, which was at least a big step ahead of EBCDIC. But this standardized only the lower 128 characters (7 Bit) and lacked at some characters for almost any language other than English. It was tried to put a small number of these additional letters into the positions of irrelevant characters like „@“, „[„, „~“, „$“ etc. And software vendors started to make use of the upper 128 characters. Commodore, Atari, MS-DOS, Apple, NeXT, TeX and „any“ software came up with a specific way for that, often specific for a language region.

These solutions where incompatible with each other between different software systems, sometimes even between versions or language versions of the same software. Remember that at that time networks were unusual and when they existed, they were proprietary to the operating system with bridge solutions being extremely difficult to implement. Even formats for floppy disks (the three-dimensional incarnations of the save button) had proprietary formats. So it did not hurt so much to have incompatible encodings.

But relatively early X11 which became the typical graphical system for Unix and later Linux started to use standard encodings like the ISO-8859-x family, UTF-8 and UTF-16. Linux was already on ISO-8859-1 in version 0.99 in the early 90es and never tried to invent its own character encoding. Thank god for that….

Today all relevant systems have moved to Unicode standard and standardized encodings like ISO-8869-x, UTF-8, UTF-16… But MS-Windows has done that only partially. The graphical system is using modern encodings or at leas Cp1252, which is a decent approximation. But the text based system with the black window, in which CMD is running, is still using encodings from the MS-DOS times more than 30 years ago, like Cp850. This results in a break within the system, which is at least very annoying, when working with cygwin or CMD-windows.

Those who have a lot of courage can change this in the registry. Just change the entries for OEMCP and OEMHAL in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage simultaneously. One of them is for input, the other one for output. So if you change only one, you will even get inconsistencies within the window… Sleep well with these night mares. 🙂
Research in the internet has revealed that some have tried to change to utf-8 (CP65001) and got a system that could not even boot as a result. Try it with a copy of a virtual system without too much risk, if you like… I have not verified this, so maybe it is just bad rumors to create damage for a great company that has brought is this interesting zoo of encodings within the same system. But anyway, try it at your own risk.
Maybe something like chcp and chhal can work as well. I have not tried that either…

It is up to you if you consider this whole issue a bug or a feature.

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