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#! /bin/bash
#############################################
# Script to flash IP V4 address on PWR or ACT led
#
# Each 3 digit group of IP to be displayed is shown by:
# A long flash then
# Digits shown by the number of short flashes (zero is 10 flashes)
# A short pause
# so .102 is 1 long flash, 1 flash, pause, 10 flashes, pause, 2 flashes
#
# "Heartbeat" flashes means not yet got a valid IP
#############################################
NWINTERFACE=                              # blank or eg "wlan0", "eth0"
SHOWIPGROUP1=Y                            # 1st group eg 192    }
SHOWIPGROUP2=Y                            # 2nd group eg 168    }
SHOWIPGROUP3=Y                            # 3rd group eg 0      } 192.168.0.22
SHOWIPGROUP4=Y                            # 4th group eg 22     }

# Should not need to change anything below here
DIR="/sys/class/leds"                     # where the led control files are
MAXTRIES=20                               # Attempts to discover a valid IP ~3s each
LONGPAUSE=3                               # Long flash between IP groups (seconds)
SHORTPAUSE=0.6                            # Pause between digits
DOT=0.15                                  # Duration of a single short flash
#############################################
# Functions

setled() {                                # Adjustments to LED settings
   echo $2 | sudo tee $DIR/$LED/$1 >/dev/null
}

clr() {                                   # Turn LED off
   setled trigger none
   setled brightness $off
   sleep $LONGPAUSE
}

longflash() {                             # long flash between IP groups
   setled brightness $on
   sleep $LONGPAUSE
   setled brightness $off
   sleep $DOT
}

showdigit() {                             # Flash a number of times
   printf " %d  "  "$1"
   local i=$( (( "$1" == 0 )) && echo 10 || echo "$1")
   while (( i > 0 ))
   do
      setled brightness $on
      sleep $DOT
      setled brightness $off
      sleep $DOT
      (( i = i - 1 ))
   done
   sleep $SHORTPAUSE                      # pause between digits
}

validip() {     # Most of this function from Mitch Frazier linuxjournal.com
   IP=$(ifconfig $NWINTERFACE | grep broadcast |head -1 |tr -s ' '| cut -d ' ' -f 3)  # only the first if more than 1
   local  stat=1
   local  ip=$IP
   if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]  # not full regex for IP
   then
      OIFS=$IFS
      IFS='.'
      ip=($ip)
      IFS=$OIFS
      [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
      stat=$?
   fi
   return $stat
}

checkmodel() {
   model=$(cat /sys/firmware/devicetree/base/model | cut -d " " -f 3)
   if [[ "$model" == "Zero" ]]
   then
      on=0; off=1                         # Pi Zero LED on/off logic is reversed
      LED=led0                            # Use the ACT LED
   else
      on=1; off=0
      LED=led1                            # Use the PWR LED
   fi
}

#############################################
# Main code

checkmodel                                # Ensure the right LED control logic

saved_trigger=$(cat $DIR/$LED/trigger | sed -e '{s/^.*\[//}' | sed -e '{s/\].*//}')  # Make a note of the current trigger
trap 'setled trigger $saved_trigger; exit' EXIT SIGINT SIGHUP    # Put it back when we exit

i=0
setled trigger heartbeat
while ! validip $IP                       # get IP address
do
   (( i = i +1 ))
   if (( i > $MAXTRIES ))
   then
      echo Too many attempts to find IP - giving up
      exit 1
   fi
   sleep $LONGPAUSE
done
printf "IP address is %s\n" $IP

clr                                       # Turn led off for a while first

for group in {1..4}                       # Each of four groups of ip address
do
   showthis=SHOWIPGROUP${group}           # do we want to show this IP group?
   if [ ${!showthis} == "Y" ]
   then
      longflash                           # long flash between groups
      this=$(echo $IP | cut -d '.' -f $group)   # get this group
      printf "IP group %d (%d) " $group $this
      for (( j=0; j<${#this}; j++ ))      # each digit in turn
      do
         showdigit "${this:$j:1}"         # display the digit
      done
      printf "\n"
   fi
done

clr                                       # Turn led off for a while at the end
echo Finished