#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>

struct termios orig_termios;

void disableRawMode() {
    tcsetattr(STDIN_FILENO, TCSANOW, &orig_termios);
    printf("Term attributes restoredn");
}

void enableRawMode() {
    tcgetattr(STDIN_FILENO, &orig_termios);

    struct termios new_termios;

    memcpy(&new_termios, &orig_termios, sizeof(new_termios));
    new_termios.c_lflag &= ~ECHO;
    tcsetattr(STDIN_FILENO, TCSAFLUSH, &new_termios);

//
    if (new_termios.c_iflag & BRKINT)
      puts("BRKINT is set");
    else
      puts("BRKINT is not set");
    if (new_termios.c_cflag & PARODD)
      puts("Odd parity is used");
    else
      puts("Even parity is used");
    if (new_termios.c_lflag & ECHO)
      puts("ECHO is set");
    else
      puts("ECHO is not set");
//
}

int main(void)
{
    enableRawMode();
    if(atexit(disableRawMode)) printf("Error in atexit().n");
    return 0;
}

$ ./atexit_test
BRKINT is set
Even parity is used
ECHO is not set
Term attributes restored

$ timeout 3s ./atexit_test
BRKINT is set
Even parity is used
ECHO is not set
Term attributes restored

$ sudo su -p - root bash -c "/home/programer/media/atexit_test/atexit_test"
BRKINT is set
Even parity is used
ECHO is not set
Term attributes restored

$ sudo timeout 3s ./atexit_test
$
$ sudo timeout 3s ./atexit_test; echo $?
124

tcsetattr(STDIN_FILENO, TCSAFLUSH, &new_termios);

if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &new_termios) == -1) {
        int errsv = errno;
        printf("%d",errsv);
    }