On Mon, 22 Jan 2018 16:32:24 +0000, RobH  declaimed the
following:

>>
>I have exported the GPIO17 pin and it does show up ok, but when I do
>echo echo out > direction OUT or out, I get
>-bash: echo: write error: Invalid argument.

 You are running as root, are you not? You are also /in/ the gpio17
subdirectory?

 Try with quotes around "out" (I noticed some differences being used in
syntax between the web sites)

(as root):
 echo "out" > direction

 Dug up my RPi-3, and running via a session from Putty:

pi@raspberrypi:~$
pi@raspberrypi:~$ sudo su root
root@raspberrypi:/home/pi# cd /sys/class/gpio
root@raspberrypi:/sys/class/gpio# ls
export  gpiochip0  gpiochip100  unexport
root@raspberrypi:/sys/class/gpio# echo 17 > export

 Per the diagrams, GPIO17 is connector pin 11 (and pin 9 is ground)

root@raspberrypi:/sys/class/gpio# ls
export  gpio17  gpiochip0  gpiochip100  unexport
root@raspberrypi:/sys/class/gpio# cd gpio17
root@raspberrypi:/sys/class/gpio/gpio17# ls
active_low  device  direction  edge  subsystem  uevent  value
root@raspberrypi:/sys/class/gpio/gpio17# ls -l
total 0
-rwxrwx--- 1 root gpio 4096 Jan 22 11:54 active_low
lrwxrwxrwx 1 root gpio    0 Jan 22 11:54 device -> ../../../3f200000.gpio
-rwxrwx--- 1 root gpio 4096 Jan 22 11:54 direction
-rwxrwx--- 1 root gpio 4096 Jan 22 11:54 edge
lrwxrwxrwx 1 root gpio    0 Jan 22 11:54 subsystem ->
../../../../../../class/gpio
-rwxrwx--- 1 root gpio 4096 Jan 22 11:54 uevent
-rwxrwx--- 1 root gpio 4096 Jan 22 11:54 value
root@raspberrypi:/sys/class/gpio/gpio17# cat active_low direction edge
uevent value
0
in
none
0
root@raspberrypi:/sys/class/gpio/gpio17# echo out > direction

 No quotes needed in my test

root@raspberrypi:/sys/class/gpio/gpio17# cat active_low direction edge
uevent value
0
out
none
0
root@raspberrypi:/sys/class/gpio/gpio17# echo 1 > value
root@raspberrypi:/sys/class/gpio/gpio17# cat active_low direction edge
uevent value
0
out
none
1

 DVM read 3.28V between connector pins 11 and 9 (Not easy holding the
meter probes on the pins, especially as my unit is in a case and the access
slot isn't that wide)

root@raspberrypi:/sys/class/gpio/gpio17# echo 0 > value
root@raspberrypi:/sys/class/gpio/gpio17# cat active_low direction edge
uevent value
0
out
none
0

 DVM read 0.00V between connector pins 11 and 9

root@raspberrypi:/sys/class/gpio/gpio17# cd ..
root@raspberrypi:/sys/class/gpio# echo 17 > unexport
root@raspberrypi:/sys/class/gpio#


{Note: My SD card is still running a Jessie release; I need to spend a day
reflashing and configuring the latest Raspbian, which I think is now up to
Stretch}
--
 Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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