Print the key codes on the terminal as you type

keycodes.c

// Inspired by http://viewsourcecode.org/snaptoken/kilo/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <ctype.h>

struct termios orig_termios;

void unsetupTerminal() {
  tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios);
}

void setupTerminal() {
  struct termios termios;

  tcgetattr(STDIN_FILENO, &orig_termios);
  termios = orig_termios;
  // Turn off:
  //   ECHO: echo mode (don't print letter)
  //   ICANNON: canonical mode (don't wait for enter)
  //   ISIG: Ctrl-C /Ctrl-Z - send key combination to the application
  //   IEXTEN: Ctrl-V - send key combination to the application
  termios.c_lflag &= ~(ECHO | ICANON | ISIG | IEXTEN);
  // Tirn off:
  //   IXON: Ctrl-S /Ctrl-Q - send key combination to the application
  //   ICRNL: Ctrl-M - send key combination to the application
  termios.c_iflag &= ~(IXON | ICRNL);
  tcsetattr(STDIN_FILENO, TCSAFLUSH, &termios);
  atexit(unsetupTerminal);
}

int main() {
  char c;

  setupTerminal();
  while (read(STDIN_FILENO, &c, 1) == 1) {
    if (iscntrl(c)) {
      printf("%d\n", c);
    } else {
      printf("%d ('%c')\n", c, c);
    }
  }
  return 0;
}