My terminal only executes "printf" when application end

i have this code but my terminal only executes "printf("ok"); when I quit my application, how can I fix it?

terminal in loop (?)

#include <stdio.h>
#include <GL/freeglut.h>
#include <GL/gl.h>

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowPosition(0, 0);
    glutInitWindowSize(400, 400);
    glutCreateWindow("Hello");
    printf("ok");
    glutMainLoop();
return 0; 
}

example