Raspberry Pi

https://www.raspberrypi.org/documentation/installation/installing-images/linux.md

df -h
sudo umount /dev/sdb1
sudo dd bs=4M if=2015-11-21-raspbian-jessie.img of=/dev/sdb
sudo dd bs=4M if=/dev/sdb of=from-sd-card.img
truncate --reference 2015-11-21-raspbian-jessie.img from-sd-card.img
diff -s from-sd-card.img 2015-11-21-raspbian-jessie.img
sync

sudo raspi-config

user: pi
pass: raspberry

/etc/default/keyboard:

XKBLAYOUT="us"

#!/bin/bash
cpuTemp0=$(cat /sys/class/thermal/thermal_zone0/temp)
cpuTemp1=$(($cpuTemp0/1000))
cpuTemp2=$(($cpuTemp0/100))
cpuTempM=$(($cpuTemp2 % $cpuTemp1))
 
echo CPU temp"="$cpuTemp1"."$cpuTempM"'C"
echo GPU $(/opt/vc/bin/vcgencmd measure_temp)

sudo iwlist wlan0 scan|more

sudo nano /etc/network/interfaces

allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
  ssid="YOURSSID"
  psk="YOURPASSWORD"
}

sudo ifdown wlan0
sudo ifup wlan0

http://www.rpiblog.com/2014/03/installing-oracle-jdk-8-on-raspberry-pi.html

http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

download jdk-8-linux-arm-vfp-hflt.tar.gz for Linux ARM v6/v7 Hard Float ABI

sudo tar zxvf jdk-8-linux-arm-vfp-hflt.tar.gz -C /opt
sudo update-alternatives --install /usr/bin/javac javac /opt/jdk1.8.0/bin/javac 1
sudo update-alternatives --install /usr/bin/java java /opt/jdk1.8.0/bin/java 1
sudo update-alternatives --config javac
sudo update-alternatives --config java
java -version
javac -version

1. Enable I2C:

sudo raspi-config
"7 Advanced Options" / "A6 I2C"

2. Install I2C-tools:

sudo apt-get install python-smbus
sudo apt-get install i2c-tools

3. Check Pi starts I2C automatically in /etc/modules:

i2c-dev

4. Check user has group (change pi to required):

sudo adduser pi i2c

5. Update to latest packeges:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade

6. reboot

7. Check RTC appears on channel 68:

sudo i2cdetect -y 1

8. Add at the end of /boot/config.txt:

dtoverlay=i2c-rtc,ds3231

9. Don't need hwclock and ntp:

sudo apt-get purge fake-hwclock

sudo apt-get purge ntp
sudo apt-get install ntpdate

10. Set date/time:

sudo dpkg-reconfigure tzdata
sudo date -s "2 SEPTEMBER 2016 10:00:00"
sudo hwclock -w  

11. Add the line in /etc/rc.local (above “exit 0”):

/sbin/hwclock -s

12. Change in /etc/init.d/hwclock.sh:

HWCLOCKACCESS=no

13. reboot

Done!

14. Other info commands:

sudo dmesg | grep rtc
sudo cat /proc/driver/rtc