What is the clear program?

Typing clear at the terminal clears your screen. How does this program work? The implementation is tiny:

#include <stdio.h>
int main() {
  return 0;

This magic string is composed of two bytes: 27, then 'c'. Byte 27 is ESC in the ACSII table, and it’s understood by the terminal as an escape sequence. It then expects further characters to specify the command; we give it 'c' which clears the screen.