Print input characters in raw terminal mode. Useful when developing shells/readline etc.

print_raw_term.c

#include <unistd.h>
#include <ctype.h>
#include <stdio.h>
#include <termios.h>
#include <string.h>

int main(void)
{
    struct termios tty_attr;

    tcgetattr(STDIN_FILENO, &tty_attr);
    // flags taken from "man 3 termios"
    tty_attr.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
        | INLCR | IGNCR | ICRNL | IXON);
    tty_attr.c_oflag &= ~OPOST;
    tty_attr.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
    tty_attr.c_cflag &= ~(CSIZE | PARENB);
    tty_attr.c_cflag |= CS8;
    // read min 1 character at a time, no timeout
    tty_attr.c_cc[VTIME] = 0;
    tty_attr.c_cc[VMIN] = 1;
    tcsetattr(STDIN_FILENO, TCSANOW, &tty_attr);

    setvbuf(stdout, NULL, _IONBF, 0);

    while (1) {
        char c;
        read(STDIN_FILENO, &c, 1);
        if (isprint(c)) {
            printf("%c", c);
        } else {
            printf("\\x%02x", c);
        }
    }
}