sysfs function for accessing gpio in ubuntu

sridar

I am trying turn on led using gpio pins.

echo "26" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio26/direction
echo 1 > /sys/class/gpio/gpio26/value
echo 0 > /sys/class/gpio/gpio26/value
echo "26" > /sys/class/gpio/unexport

After unexporting, led is again turning on.

Kindly help me to resolve this issue.