General Purpose GPIO

* make pin 23 an output pin:
echo out >/sys/class/gpio/gpio23/direction

* set the pin direction with an initial value:
echo  low >/sys/class/gpio/gpio23/direction
echo high >/sys/class/gpio/gpio23/direction

* set the pin output on or off:
echo 1 >/sys/class/gpio/gpio23/value
echo 0 >/sys/class/gpio/gpio23/value

* invert the pin logic:
echo 1 >/sys/class/gpio/gpio23/active_low

GPIO Without Root

export pin 23 so all pin manipulations do not require root privilege:
gpio_control 23 export