how to print on edison stdout via arduino IDE(sketch.elf)

I write a arduino program via Arduino IDE and i need it to print data in the stdout of edison. Because I will manually start the program (/sketch/sketch.elf) in the shell of edison.

But I tried printf and system("echo xxx"), they will not print any data on shell. It seems the arduino IDE redirect the stdout. Does anyone know how to make the adruno program to print data on edison stdout?