That's the section heading on page 302 of Derek Molloy's second edition 
"Exploring Beaglebone"
 
I found the section lacking in information on exactly how to do this.  A web 
search showed up the following pages.
 
https://github.com/adafruit/adafruit-beaglebone-io-python/issues/137
 
https://linuxize.com/post/how-to-add-user-to-group-in-linux/
 
https://github.com/cnobile2012/RobotControl/tree/master/contrib
 
I'm still not sure of the actual process with this revision of the OS.
debian@ebb:~/lazarus$ uname -a
Linux ebb 4.14.108-ti-r136 #1stretch SMP PREEMPT Mon Jun 8 15:38:30 UTC 2020 
armv7l GNU/Linux
 
Robert Nelson mentions 4.11+ as having support for "it" so is any of what is in 
the first link needed?  
"it's created after you export 0 (or 1) in the pwm system node. only v4.11.x+ 
has the udev patch for permissions. (didn't want to break older userspace, we 
still need to fix bonescript before i backport that patch to v4.4.x/v4.9.x)"
 
I don't have a
/etc/udev/rules.d/80-gpio-permissions.rules
 
So I'm thinking I do have to create that file with 
KERNEL=="gpio*", SUBSYSTEM=="gpio", ACTION=="add", 
PROGRAM="/usr/local/bin/udev-gpio-permissions.sh"
 
And then create the shell script as outlined but with user debian in group 
gpio?  
Eg: 
chown -R nick:digital /sys/devices/gpio
 
becomes 
chown -R debian:gpio /sys/devices/gpio
 
 
That's where it starts to fall apart for me as far as instructions go.  There's 
an assumption of knowledge about something except I don't know what that is. 
 
debian@ebb:~/lazarus$ ls -al  /etc/udev/rules.d/
total 84
drwxr-xr-x 2 root root 4096 Apr 24 17:05 .
drwxr-xr-x 4 root root 4096 Jul 14  2020 ..
-rw-r--r-- 1 root root  372 Jul 10  2020 10-of-symlink.rules
-rw-r--r-- 1 root root   48 Oct  7  2018 50-hidraw.rules
-rw-r--r-- 1 root root   44 Oct  7  2018 50-spi.rules
-rw-r--r-- 1 root root  142 Oct  7  2018 60-omap-tty.rules
-rw-r--r-- 1 root root  921 Jul 10  2020 80-eeprom-noroot.rules
-rw-r--r-- 1 root root  569 Feb 25 06:10 80-gpio-noroot.rules
-rw-r--r-- 1 root root  308 Feb 25 06:10 80-i2c-noroot.rules
-rw-r--r-- 1 root root 2113 Feb 25 06:10 81-pwm-noroot.rules
-rw-r--r-- 1 root root  339 Feb  1  2019 82-gpio-config-pin.rules
-rw-r--r-- 1 root root  359 Jul 10  2020 83-eqep-noroot.rules
-rw-r--r-- 1 root root  509 Aug 15  2018 84-gpio-noroot.rules
-rw-r--r-- 1 root root  188 Aug 15  2018 85-gpio-noroot.rules
-rw-r--r-- 1 root root 1414 Jul 10  2020 86-remoteproc-noroot.rules
-rw-r--r-- 1 root root  352 Jul 10  2020 86-rpmsg-noroot.rules
-rw-r--r-- 1 root root  218 Jul 10  2020 87-iio-noroot.rules
-rw-r--r-- 1 root root  308 Feb 25 06:10 88-leds-noroot.rules
-rw-r--r-- 1 root root  855 Oct  7  2018 beagle-tester.rules
-rw-r--r-- 1 root root   97 Oct  7  2018 tisdk.rules
-rw-r--r-- 1 root root  108 Oct  7  2018 uio.rules
debian@ebb:~/lazarus$
 
 
From 
debian@ebb:~/lazarus$ more /etc/group
I get:  
gpio:x:999:debian,node-red,john
 
What else is required so I don't have to use sudo for C, Lazarus or python 
programs to access GPIO?  
 
debian@ebb:~/lazarus$ cat /etc/udev/rules.d/80-gpio-noroot.rules
# /etc/udev/rules.d/80-gpio-noroot.rules
#
# Stolen from Pi: 
https://github.com/RPi-Distro/raspberrypi-sys-mods/blob/master/etc.armhf/udev/rules.d/99-com.rules#L9-L14
#
SUBSYSTEM=="gpio", GROUP="gpio", MODE="0660"
SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c '\
        chown -R root:gpio /sys/class/gpio && chmod -R 770 /sys/class/gpio;\
        chown -R root:gpio /sys/class/gpio/*export && chmod -R 220 
/sys/class/gpio/*export;\
        chown -R root:gpio /sys/devices/virtual/gpio && chmod -R 770 
/sys/devices/virtual/gpio;\
        chown -R root:gpio /sys$devpath && chmod -R 770 /sys$devpath\
'"
 
Or is it all as simple as this which is 7 years old:
https://github.com/cnobile2012/RobotControl/tree/master/contrib
Trouble with the read me here is that it doesn't show what the end result 
should look like and I already have the  80-gpio-noroot.rules file.
 
Very confused…
John
 

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