Hello everyone I am having a little issue with my bandwidth script and I am not sure really what the issue is. I was hoping to get a fresh set of eyes on it. Almost everything works correctly but I am getting the wrong value for data going out. The calculations and results for the IN results is working perfectly but I am getting the wrong value for total MB going out and sometimes it is a negative value and that throws off the bandwidth calculations. I have removed the IP address for security purposes. Here is the script below, any help you could provide would be much appreciated!
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while true
do

bytes_beforeTOT=0;bytes_afterTOT=0;
bytes_beforeOUT=0;bytes_afterOUT=0;
bytes_beforeIN=0;bytes_afterIN=0;
data=0.01;

bytes_beforeOUT=$((snmpget -v2c -c primealerts (IP ADDRESS) 1.3.6.1.2.1.2.2.1.16.529) | awk '{print $4}')
bytes_beforeIN=$((snmpget -v2c -c primealerts (IP ADDRESS) 1.3.6.1.2.1.2.2.1.10.529) | awk '{print $4}')

#####################
#Conversion for Out Data Before

KilobitOut=$((bytes_beforeOUT / 1024))
MegabitOut=$((KilobitOut / 1024))

#########################
#Conversion for In Data Before

KilobitIn=$((bytes_beforeIN / 1024))
MegabitIn=$((KilobitIn / 1024))

#########################
sleep 300

bytes_afterOUT=$((snmpget -v2c -c primealerts (IP ADDRESS) 1.3.6.1.2.1.2.2.1.16.529) | awk '{print $4}')
bytes_afterIN=$((snmpget -v2c -c primealerts (IP ADDRESS) 1.3.6.1.2.1.2.2.1.10.529) | awk '{print $4}')

#########################
#Conversion for Out Data After

KilobitOutAfter=$((bytes_afterOUT / 1024))
MegabitOutAfter=$((KilobitOutAfter / 1024))

#########################
#Conversion for In Data After

KilobitInAfter=$((bytes_afterIN / 1024))
MegabitInAfter=$((KilobitInAfter / 1024))

#########################
#Calculations

TotalMbitIn=$(($MegabitInAfter - $MegabitIn))
TotalMbitOut=$(($MegabitOutAfter - $MegabitOut))

###################################
#New Conversion Gbit per second In


MbitConTotal=$((TotalMbitIn * 8))
MbitPerSecond=$(echo "$MbitConTotal / 300" | bc -l)
GbitPerSecond=$(echo "$MbitPerSecond / 1000" | bc -l)

echo "$TotalMbitIn total megabits In"
echo "$TotalMbitOut total megabits Out"


if [ 1 -eq "$(echo "${GbitPerSecond} >= ${data}" | bc)" ]
then
GbsIn=$(printf "%0.2f\n" "$GbitPerSecond")
echo "$GbsIn IN"
else
echo "0.01 IN"

fi



###################################
#New Conversion Gbit per second Out


MbitConTotalOut=$((TotalMbitOut * 8))
MbitPerSecondOut=$(echo "$MbitConTotalOut / 300" | bc -l)
GbitPerSecondOut=$(echo "$MbitPerSecondOut / 1000" | bc -l)

if [ 1 -eq "$(echo "${GbitPerSecondOut} >= ${data}" | bc)" ]
then
GbsOut=$(printf "%0.2f\n" "$GbitPerSecondOut")
echo "$GbsOut OUT"
else
echo "0.01 OUT"

fi



echo
date +'%r'
echo "END OF RUN"
echo

done

You mean that MbitConTotalOut is sometimes negative?

There are a lot of calculations in that script. Why don't you just echo all intermediate values that lead to MbitConTotalOut? That should tell you quickly where the error is.

Or run the script with the -x option, e.g. bash -x bandwidthscript. This will output all lines that are executed, and all values that are used.