APRS telemetry to INET v2

#!/bin/bash
#Define login info
user=yourHAMSIGN
password=passcode

#Define object user info
senduser=yourHAMSIGN

#Define APRS-IS server
server=poland.aprs2.net
port=14580

#Define station location
lat=4146.72N
lon=01213.80E

#Define data
comment="QTH"
data="$usersend>APN100,TCPIP*:=${lat}/${lon}-${comment}"

#Authentication variable
aprsauth="user $user pass $password"

#Read raspberry-pi CPU temperature
tempraw=/opt/vc/bin/vcgencmd measure_temp #Read pi temperature
tempfloat="$(echo "$tempraw" | awk -F= '{print $2}' | awk -F\' '{print $1}')" #Filter result to numbers only

#Aprs telemetry protocol accepts 3 whole (int) numbers only so we need
#to convert the result (tempfloat) into 3 whole numbers. So if tempraw=40.3, it will
#convert it to 403. If tempraw=8.5, it will convert it to 85 and we'll add the leading zero
#to create 3 number format 085 later bellow.
temp="$(echo "$tempfloat * 10" | bc | awk -F. '{print $1}')"

#Project comment
projectcomment=Rpi temperature

#Generate telemetry strings
#Read data and put it into variable
#%s means string
#%03d means prepend up to 3 zeroes, so if the value is 8, you'll get 008, if the value is 80, you'll get 080 etc.
#This needs to be done or APRS will deny the packets as invalid. The other things is, everytime you send the telemetry
#a sequence number has to change, it's defined as T# in a APRS protocol. We will automate this next.

#Check if file exist
if [ ! -f "/tmp/sequence_number.txt" ]; then
 touch /tmp/sequence_number.txt
fi

#Read sequence number. Everytime the scripts runs, the number will rise by 1 until it comes
#to 1000 and then returns back to 0. Everytime the script will run, a sequence number will change.
read num < /tmp/sequence_number.txt
num=$((num + 1))
if (( num == 1000 )); then
 num=0
fi

#Finally, we can start assembling the data.
#$usersend goes to %s, $num goes to first %03d and $temp goes to the last %03d in the string.
printf -v t1 "%s>APN001,TCPIP*:T#%03d,%03d,000,000,000,000,00000000" "$senduser" "$num" "$temp"

#Define telemetry parameters
t2="$user>APN001,TCPIP*::$senduser :PARM.CPU Temp"

#Define telemetry units
t3="$user>APN001,TCPIP*::$senduser :UNIT.Deg.C"

#Add telemetry coefficient so the APRS protocol can convert your raw values into real value.
#We get the value in 3 whole numbers and we need to define coefficient so the APRS protocol
#will know how to display the value. We add 0.1 to the second field, means
#if the value is 452, the temperature will be displayed as 45.2
t4="$user>APN001,TCPIP*::$senduser :EQNS.0,0.1,0,0,0,0,0,0,0,0,0,0,0,0,0"

#Send bits and project comment
t5="$user>APN001,TCPIP*::$senduser :BITS.00000000,$projectcomment"

#Another tricky part is, $senduser total lenght has to be 9 characters. For example
#If my $senduser=S55MA-10 means it's only 8 characters long and we need to add 1 space to it. S55MA-10 :PARM
#If my $senduser=S55MA means it's only 5 characters long and we need to add 4 spaces to it S55MA    :PARM
#The same goes for UNIT, EQNS and BITS

#Send data to the server
#For telemetry to work we need to have an object before, from previous script.
#We'll only send an object and telemetry non value data every hour so we don't spam the network.
#We need to compare dates to see if 1 hour is past.

#Check if file exist
if [ ! -f "/tmp/date.txt" ]; then
   echo 0 > /tmp/date.txt
fi

#calculate time difference
read olddate < /tmp/date.txt
date="$(date +%s)"
diff="$(echo "$date - $olddate" | bc)"

#If 3600 is past, execute the first command, else other
if [ "$diff" -gt 3600 ]; then
   printf "%s\n" "$aprsauth" "$data" | ncat --send-only $server $port #this is your QTH object from the first script
   printf "%s\n" "$aprsauth" "$t1" "$t2" "$t3" "$t4" "$t5" | ncat --send-only $server $port
   echo "$date" > /tmp/date.txt
else
   printf "%s\n" "$aprsauth" "$t1" | ncat --send-only $server $port
fi
#Write the last sequence number.
echo "$num" > /tmp/sequence_number.txt