Trying to get script working for Disk check and Deluge - linux

Question

I managed to get this script working earlier but then it stopped working and now I always get this error and the logs don't show any information the .log file is empty
My script was working fine until I changed { df -k ${fileSystem}|tail -n1 } to { quota -u |tail -n1 } because it shows the correct usage assigned to me instead of the entire seedbox
Check Entire Seedbox disk free
user#hera:~/scripts$ df -k /home20/<user>|tail -n1
/dev/sdu1 15616058976 3311158640 12303321368 22% /home20
Check Seedbox Slot only disk free
user#hera:~/scripts$ quota -u <user>|tail -n1
/dev/sdu1 1629501728 1953497088 1953497088 4344 0 0
Log file
tail: deluge-disk-check.log: file truncated
[empty]
Error message
./deluge-disk-check.sh: line 23: let: freeSpacePct=100*/: syntax error: operand expected (error token is "/")
my script
#!/bin/bash
exec 3>&1 4>&2
trap 'exec 2>&4 1>&3' 0 1 2 3
exec 1>/home/<user>/scripts/deluge-disk-check.log 2>&1
# Adjust these parameters to your system
fileSystem="/home/<user>" # Filesystem you want to monitor
minFreeSpace1="78" # Seedbox Free space 1st threshold percentage
minFreeSpace2="77" # Seedbox Free space 2nd threshold percentage
checkInterval="3600" # Interval between checks in seconds
SERVICE='deluged'
while (:); do
# Get the output of df -k and put in a variable for parsing
dfOutPut=$(df -k ${fileSystem}|tail -n1)
# Exctract the fields containing total and available 1K-blocks
totalBlocksKb=$(echo "${dfOutPut}" | awk '{print $2}')
availableBlocksKb=$(echo "${dfOutPut}" | awk '{print $4}')
# Calculate percentage of free space
let freeSpacePct=100\*${availableBlocksKb}/${totalBlocksKb}
# Check if free space percentage is below threshold value
if [ "${freeSpacePct}" -lt "${minFreeSpace1}" ]; then
date +'%Y-%m-%d %H:%M:%S'
echo "You only have ${freeSpacePct}% free space on seedbox"
# Check whether the instance of thread exists:
if ps ax | grep -v grep | grep $SERVICE > /dev/null
then
echo "Deluge is running, Is there free space on device?"
pkill deluge
echo -e "No, Trying to stop Deluge...\nDeluge stopped, exiting"
else
if [ "${freeSpacePct}" -lt "${minFreeSpace2}" ]; then
echo "refreshing data..."
echo "Deluge is not running, Is there free space on device?"
echo "Yes, Threshold value is now ${minFreeSpace2}%"
echo "Trying to restart Deluge ..." && app-deluge restart
echo "Deluge is running, exiting"
sleep ${checkInterval}
fi
fi
fi
done

Answer 1

On line 23:
let freeSpacePct=100\*${availableBlocksKb}/${totalBlocksKb}
For arithmetic evaluations, use $(( ... ))) like this:
let freeSpacePct=$(( 100 * ${availableBlocksKb} / ${totalBlocksKb} ))
or more simply (without ${...} around variable names):
let freeSpacePct=$(( 100 * availableBlocksKb / totalBlocksKb ))