How to detect the status of the capslock in linux programmatically?

by coty_beier , in category: General Help , 7 months ago

How to detect the status of the capslock in linux programmatically?

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2 answers

Member

by brock , 7 months ago

@coty_beier 

In Linux, you can programmatically detect the status of the Caps Lock key by reading the state of the relevant keyboard LED. Here's a step-by-step guide on how to achieve this using the C programming language:

  1. Include the necessary header files at the beginning of your source code: #include
  2. Implement the following function to query the Caps Lock status: int isCapsLockOn(Display* display) { XKeyboardState xkb; XGetKeyboardControl(display, &xkb); return (xkb.led_mask & (1 << 0)); // The first bit corresponds to Caps Lock (0 indexed) }
  3. In your main function, open a connection to the X display server and call the isCapsLockOn function to check the Caps Lock status: int main() { Display* display = XOpenDisplay(NULL); // Open a connection to the X display server int capsLockOn = isCapsLockOn(display); printf("Caps Lock status: %s ", capsLockOn ? "ON" : "OFF"); XCloseDisplay(display); // Close the connection to the X display server return 0; }
  4. Compile the code: gcc -o capslock_status_capslock status.c -lX11
  5. Run the compiled program to get the Caps Lock status: ./capslock_status


The program will output "Caps Lock status: ON" or "Caps Lock status: OFF" based on the Caps Lock key's state.

Member

by gaston , 2 months ago

@coty_beier 

Here are the corrected steps to detect the caps lock status in Linux programmatically using the C programming language:

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#include <X11/XKBlib.h>
#include <X11/Xlib.h>

int isCapsLockOn(Display* display) {
    XkbStateRec state;
    XkbGetState(display, XkbUseCoreKbd, &state);
    return (state.locked_mods & ShiftLockMask); // Check if ShiftLockMask is set
}

int main() {
    Display* display = XOpenDisplay(NULL);
    int capsLockOn = isCapsLockOn(display);
    printf("Caps Lock status: %s
", capsLockOn ? "ON" : "OFF");
    XCloseDisplay(display);
    return 0;
}


To compile and run the code:

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gcc -o capslock_status capslock_status.c -lX11 -lX11-xkb
./capslock_status


This code snippet now correctly utilizes the XkbGetState function from the X Keyboard Extension library (-lX11-xkb) to query the caps lock state instead of XGetKeyboardControl.


Ensure that the X11 development libraries are installed on your system to compile and run this code successfully.