View source for Talk:Create SD Image Version 0.8.1


==Set Time Zone==

Install perl DateTime module

apt-get install libdatetime-perl



==Disable the onboard WiFi==

To completely disable the onboard WiFi from the firmware on the Pi3, in /boot/config.txt add
 dtoverlay=pi3-disable-wifi
https://raspberrypi.stackexchange.com/questions/43720/disable-wifi-wlan0-on-pi-3

==Make sure ntpd is working==

Add:
/sbin/iptables -t mangle -I POSTROUTING 1 -o wlan0 -p udp --dport 123 -j TOS --set-tos 0x00

to the file
/etc/rc.local

See SR-71's comment here:
https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=141454&p=950388


== Fix dht22_adafruit.sh and dht11_adafruit.sh ==

 # The output string looks like: Temp=13.3* Humidity=33.7%
 # First, it is split on the space into two variables 
 #        TEMP=$1
 #        HUMIDITY=$2
 
 # https://stackoverflow.com/questions/16015590/extract-number-of-variable-length-from-string
 # https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
 # Then variable expansionn is used to extract the temperature and humidity number
 # by throwing everything away before the = sign: 
 
        TEMP=${1#*=}
        HUMIDITY=${2#*=}
 #echo
 #echo TEMP $TEMP
 #echo HUMIDITY $HUMIDITY
 
 # Then, everything is thrown away after the 4th character in the string
 #
 #        TEMP=${TEMP:0:4}
 #        HUMIDITY=${HUMIDITY:0:4}
 #
 # NO!  Doesn't work for 9.9* only 10.1*
 # Try just dropping the last character, either * or %
 # https://unix.stackexchange.com/questions/144298/delete-the-last-character-of-a-string-using-string-manipulation-in-shell-script
 #
 TEMP=${TEMP%?}
 HUMIDITY=${HUMIDITY%?}
 
==Fix sqlite.sh==
 if [ "$HIVE_WEIGHT_UNITS" = "lb"  ]
 # calculate kg
 then
  if [ "$HIVE_WEIGHT" != "NULL" ]
  then
    HIVE_WEIGHT_LB=$HIVE_WEIGHT
    HIVE_WEIGHT_KG=$(printf %.2f `echo "scale=3; 
 ($HIVE_WEIGHT/2.20462)/1" | bc`)
    
  else
     HIVE_WEIGHT_KG="NULL"
     HIVE_WEIGHT_LB="NULL"
  fi
 else
 # calculate lb
  if [ "$HIVE_WEIGHT" != "NULL" ]
  then
    HIVE_WEIGHT_KG=$HIVE_WEIGHT
    HIVE_WEIGHT_LB=$(printf %.2f `echo "scale=3; 
 ($HIVE_WEIGHT*2.20462)/1" | bc`)
  else
     HIVE_WEIGHT_LB="NULL"
     HIVE_WEIGHT_KG="NULL"
  fi
 fi

==Resize (shrink) the image and make it so it will expand on the initial boot==

https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh

 #!/bin/bash
 
 usage() { echo "Usage: $0 [-s] imagefile.img [newimagefile.img]"; exit -1; }
 
 should_skip_autoexpand=false
 
 while getopts ":s" opt; do
   case "${opt}" in
     s) should_skip_autoexpand=true ;;
     *) usage ;;
   esac
 done
 shift $((OPTIND-1))
 
 #Args
 img="$1"
 
 #Usage checks
 if [[ -z "$img" ]]; then
   usage
 fi
 if [[ ! -f "$img" ]]; then
   echo "ERROR: $img is not a file..."
   exit -2
 fi
 if (( EUID != 0 )); then
   echo "ERROR: You need to be running as root."
   exit -3
 fi
 
 #Check that what we need is installed
 for command in parted losetup tune2fs md5sum e2fsck resize2fs; do
   which $command 2>&1 >/dev/null
   if (( $? != 0 )); then
     echo "ERROR: $command is not installed."
     exit -4
   fi
 done
 
 #Copy to new file if requested
 if [ -n "$2" ]; then
   echo "Copying $1 to $2..."
   cp --reflink=auto --sparse=always "$1" "$2"
   if (( $? != 0 )); then
     echo "ERROR: Could not copy file..."
     exit -5
   fi
   old_owner=$(stat -c %u:%g "$1")
   chown $old_owner "$2"
   img="$2"
 fi
 
 #Gather info
 beforesize=$(ls -lh "$img" | cut -d ' ' -f 5)
 parted_output=$(parted -ms "$img" unit B print | tail -n 1)
 partnum=$(echo "$parted_output" | cut -d ':' -f 1)
 partstart=$(echo "$parted_output" | cut -d ':' -f 2 | tr -d 'B')
 loopback=$(losetup -f --show -o $partstart "$img")
 tune2fs_output=$(tune2fs -l "$loopback")
 currentsize=$(echo "$tune2fs_output" | grep '^Block count:' | tr -d ' ' | cut -d ':' -f 2)
 blocksize=$(echo "$tune2fs_output" | grep '^Block size:' | tr -d ' ' | cut -d ':' -f 2)
 
 #Check if we should make pi expand rootfs on next boot
 if [ "$should_skip_autoexpand" = false ]; then
   #Make pi expand rootfs on next boot
   mountdir=$(mktemp -d)
   mount "$loopback" "$mountdir"
 
   if [ $(md5sum "$mountdir/etc/rc.local" | cut -d ' ' -f 1) != "0542054e9ff2d2e0507ea1ffe7d4fc87" ]; then
     echo "Creating new /etc/rc.local"
     mv "$mountdir/etc/rc.local" "$mountdir/etc/rc.local.bak"
     #####Do not touch the following lines#####
 cat <<\EOF1 > "$mountdir/etc/rc.local"
 #!/bin/bash
 do_expand_rootfs() {
   ROOT_PART=$(mount | sed -n 's|^/dev/\(.*\) on / .*|\1|p')
 
   PART_NUM=${ROOT_PART#mmcblk0p}
   if [ "$PART_NUM" = "$ROOT_PART" ]; then
     echo "$ROOT_PART is not an SD card. Don't know how to expand"
     return 0
   fi
 
   # Get the starting offset of the root partition
   PART_START=$(parted /dev/mmcblk0 -ms unit s p | grep "^${PART_NUM}" | cut -f 2 -d: | sed 's/[^0-9]//g')
   [ "$PART_START" ] || return 1
   # Return value will likely be error for fdisk as it fails to reload the
   # partition table because the root fs is mounted
   fdisk /dev/mmcblk0 <<EOF
 p
 d
 $PART_NUM
 n
 p
 $PART_NUM
 $PART_START
 
 p
 w
 EOF
 
 cat <<EOF > /etc/rc.local &&
 #!/bin/sh
 echo "Expanding /dev/$ROOT_PART"
 resize2fs /dev/$ROOT_PART
 rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
 
 EOF
 reboot
 exit
 }
 raspi_config_expand() {
 /usr/bin/env raspi-config --expand-rootfs
 if [[ $? != 0 ]]; then
   return -1
 else
   rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
   reboot
   exit
 fi
 }
 raspi_config_expand
 echo "WARNING: Using backup expand..."
 sleep 5
 do_expand_rootfs
 echo "ERROR: Expanding failed..."
 sleep 5
 rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
 exit 0
 EOF1
     #####End no touch zone#####
     chmod +x "$mountdir/etc/rc.local"
   fi
   umount "$mountdir"
 else
   echo "Skipping autoexpanding process..."
 fi
 
 #Make sure filesystem is ok
 e2fsck -p -f "$loopback"
 minsize=$(resize2fs -P "$loopback" | cut -d ':' -f 2 | tr -d ' ')
 if [[ $currentsize -eq $minsize ]]; then
   echo "ERROR: Image already shrunk to smallest size"
   exit -6
 fi
 
 #Add some free space to the end of the filesystem
 extra_space=$(($currentsize - $minsize))
 for space in 5000 1000 100; do
   if [[ $extra_space -gt $space ]]; then
     minsize=$(($minsize + $space))
     break
   fi
 done
 
 #Shrink filesystem
 resize2fs -p "$loopback" $minsize
 if [[ $? != 0 ]]; then
   echo "ERROR: resize2fs failed..."
   mount "$loopback" "$mountdir"
   mv "$mountdir/etc/rc.local.bak" "$mountdir/etc/rc.local"
   umount "$mountdir"
   losetup -d "$loopback"
   exit -7
 fi
 sleep 1
 
 #Shrink partition
 losetup -d "$loopback"
 partnewsize=$(($minsize * $blocksize))
 newpartend=$(($partstart + $partnewsize))
 parted -s -a minimal "$img" rm $partnum >/dev/null
 parted -s "$img" unit B mkpart primary $partstart $newpartend >/dev/null
 
 #Truncate the file
 endresult=$(parted -ms "$img" unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B')
 truncate -s $endresult "$img"
 aftersize=$(ls -lh "$img" | cut -d ' ' -f 5)
 
 echo "Shrunk $img from $beforesize to $aftersize"