I have made a bash script to monitor my network traffic every 10 sec using ifconfig. It must be ifconfig else I would have used a different tool.
My issue is because my counter is so high number I have to use expr
to do the calculation, however expr
is causing me some issues.
#!/bin/bash
#run for how many seconds
savefile=/root/eth0.csv
timer=10
echo "EPOCH,Interface,TX,RX,ChangeTx,ChangeRX" >> $savefile
END=8640
x=$END
while [ $x -gt 0 ]; do
ETH0RX=`ifconfig | grep eth0 -A8 | grep "RX bytes" | tr -s ' ' | cut -d':' -f2 | cut -d ' ' -f1`
ETH0TX=`ifconfig | grep eth0 -A8 | grep "RX bytes" | tr -s ' ' | cut -d':' -f3 | cut -d ' ' -f1`
#ETH0 RX
ETH0RXcurrentvalue=$ETH0RX
ETH0RXchange=$(expr $ETH0RXcurrentvalue - $ETH0RXpreviousvalue)
ETH0RXpreviousvalue=$ETH0RXcurrentvalue
#ETH0 TX
ETH0TXcurrentvalue=$ETH0TX
ETH0TXchange=$(expr $ETH0TXcurrentvalue - $ETH0TXpreviousvalue)
ETH0TXpreviousvalue=$ETH0TXcurrentvalue
epoch=`date +%s`
echo $epoch,ETH0,$ETH0TX,$ETH0RX,$(($ETH0RXchange*8)),$(($ETH0TXchange*8)) >> $savefile
sleep $timer
x=$(($x-1))
done;
My error is line 33: arithmetic syntax error
(which is done;
). The script works fine if there is no expr
, however due to big numbers I need to use expr
(I cannot use bc
).
I have fixed the issue,
As I'm trying to do an
expr
and then later on the script I do another calculation the
expr
continuously giving error because of the other line where the calculation was via echo.
so I fixed using the code below.
ETH0RXcurrentvalue=$ETH0RX
ETH0RXchange=$(expr "$ETH0RXcurrentvalue" - "$ETH0RXpreviousvalue")
ETH0RXpreviousvalue=$ETH0RXcurrentvalue
ETH0RXchange1=$(expr "$ETH0RXchange" \* "8")
echo $ETH0RXchange1
echo $ETH0TXchange1
echo $epoch,ETH0,$ETH0TX,$ETH0RX,$ETH0RXchange1,$ETH0TXchange1 >> $savefile