root@ubuntu:/sys/class/gpio# ls
export  gpiochip496  unexport
root@ubuntu:/sys/class/gpio# echo 496 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 497 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 498 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 499 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 500 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 501 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 502 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 503 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 504 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 505 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 506 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 507 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 508 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 509 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 510 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio# echo 511 > /sys/class/gpio/export
bash: echo: write error: No such device
root@ubuntu:/sys/class/gpio#