Problem with arrow keys in shell with python and java

[Qwerty]

Hello, I have a problem when I run scripts in Python and Java. When I press the arrow keys, they input ASCII characters or something similar instead of moving in the shell.

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~/Escritorio/programacion$ java Prueba
Escribe algo
^[[D^[[C^[[D^[[C^[[B^[[B^[[B^[[A^[[A^[[A^[[C^[[D^[[B^[[D^[[A^[[C^[[D^[[B^[[A^[[C^[[D^[[B^[[A^[[C^[[B^[[D^[[C^[[A^[[D^[[B^[[D^[[A^[[B^[[C^[[D^[[B^[[A^[[C^[[D^[[B^[[C^[[D^[[B^[[D^[[A^[[C^[[B^[[D^[[A^[[B^[[C^[[D^[[A^[[B^[[C^C

Code: Select all

python3 prueba.py 
Escribe algo         Hello this is an example^[[D^[[D^[[D^[[D^[[D^[[D^[[C^[[B^[[D^[[A^[[C^[[B^[[D^[[A^[[C^[[D^[[A^[[B^[[D^[[C^[[A^[[D^[[B^[[D^[[D^[[C^[[B^[[D^[[A^[[C^[[D^[[B^[[C^[[A^[[D^[[B^[[C^[[B^[[D^[[A^[[C^CTraceback (most recent call last):
  File "/home/lagt/Escritorio/programacion/prueba.py", line 1, in <module>
    a = input('Escribe algo')
KeyboardInterrupt

[dave0808]

The arrow keys work within the shell because that's part of the shell's input interpreter.

When you are running your program in Java or Python and are reading from stdin, it is your program that is accepting the input and therefore your program that needs to do something with that input.

I don't do Python, but in Java, the usual way for reading from stdin is to read input from System.in, which is an implementation of java.io.InputStream and won't provide you with "control codes". Equally with java.io.Console, which uses java.io.Reader which itself is a character based class.

Looking on stackoverflow there doesn't seem to be a definitive answer to this. You will probably need to put the console into a raw mode and somehow get hold of the raw key presses.

[spamegg]

Install the rlwrap package and run your scripts / commands with rlwrap in front.

[jacobmallll]

Hi,

If you're using Scanner or BufferedReader for input in Java, you might want to consider enabling raw mode for your terminal.

Follow this-

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import java.io.Console;

public class Prueba {
    public static void main(String[] args) {
        Console console = System.console();
        if (console != null) {
            console.printf("Escribe algo: ");
            String input = console.readLine();
            System.out.println("You entered: " + input);
        }
    }
}

It will work for you.

[dave0808]

It will work for you.

How, exactly, is this code going to do what the OP wants? As I previously stated, the Console class is a string based reader and as the OP has already discovered, this will just write control characters as the arrow keys are pressed.

[dave0808]

BTW, KeyListener is for Java UI applications (AWT, Swing) and does not work for the command line that the OP was asking about.