Hi everyone I am trying to write my GPIO pin values from terminal. However, attempting to set the value of a GPIO pin does nothing. Setting the direction of the GPIO pin to 'out' and then writing the value with 'echo 1 > value' doesn't actually change the value. 'cat value' prints 0. I am using physical pin 11 (gpio9) however it affects many other pins as well. I haven't tried absolutely every single one. My permissions on the file are set correctly as far as I can tell, and no resource is in use by any process: This shows the problem: It also appears not to be an inconsistency with between pin and file state, as the LED I have plugged into the physical pin does not illuminate either. I had it working briefly the other day. Any ideas on why toggling the values is not working would be appreciated. What can cause this issue? I am on Linaro Ubuntu 12.04. EDIT: After doing some testing I switched to Debian, where the issue did not appear. I ran the exact same commands as above, and while I noticed an inconsistency between the physical state of the pin and the value of the "value" file, the pin itself did turn the LED on. Switching back to Ubuntu afterwards gave the same results. Pin physically works, but value file is incorrect. So I suppose the question has changed to: What could cause this to happen? Previously my UDOO was running for a couple days before I found the GPIO pins were not working period.