bash script for checking out traffic via /proc/net/dev

traffic.sh

#!/bin/bash

#shows traffic on the specified device

function human_readable {
    VALUE=$1
        BIGGIFIERS=( B K M G )
    CURRENT_BIGGIFIER=0
    while [ $VALUE -gt 10000 ] ;do
        VALUE=$(($VALUE/1000))
        CURRENT_BIGGIFIER=$((CURRENT_BIGGIFIER+1))
    done
    #echo "value: $VALUE"
    #echo "biggifier: ${BIGGIFIERS[$CURRENT_BIGGIFIER]}"
    echo "$VALUE${BIGGIFIERS[$CURRENT_BIGGIFIER]}"
}

function help {
    echo -e "\nusage: $0 -I interface -w WarningBytesPerSecound -c CriticalBytesPerSecound\n\nThis plugin shows the bandwith currently used on a network interface."
    exit -1
}

###CHECKS####
# Getting parameters:
while getopts "I:w:c:h" OPT; do
    case $OPT in
        "I") DEVICE=$OPTARG;;
        "w") warning=$OPTARG;;
        "c") critical=$OPTARG;;
        "h") help;;
    esac
done

( [ "$DEVICE" == "" ] ) && \
    echo "ERROR: You must specify a interface" && help
#DEVICE=$1
IS_GOOD=0
for GOOD_DEVICE in `grep ":" /proc/net/dev | awk '{print $1}' | sed s/://`; do
    if [ $DEVICE = $GOOD_DEVICE ]; then
        IS_GOOD=1
        break
    fi
done
if [ $IS_GOOD -eq 0 ]; then
    echo "UNKNOWN: Device $DEVICE not found."
    exit 3
fi

#LIMITS
( [ "$warning" == "" ] || [ "$critical" == "" ] ) && \
    echo "ERROR: You must specify all warning and critical levels" && help

( [[ "$warning" -ge  "$critical" ]] ) && \
  echo "ERROR: critical levels must be highter than warning levels" && help




###REAL STUFF

RECEIVED=`grep $DEVICE /proc/net/dev | awk '{print $2}'`
TRANSMITTED=`grep $DEVICE /proc/net/dev | awk '{print $10}'`
TOTAL=$(($RECEIVED+$TRANSMITTED))

#echo "Transmitted: `human_readable $TRANSMITTED`"
#echo "Received: `human_readable $RECEIVED`"
#echo "Total: `human_readable $TOTAL`"

SLP=1
#echo "Sleeping $SLP to calculate speed..."
sleep $SLP

RECEIVED=`grep $DEVICE /proc/net/dev | awk '{print $2}'`
TRANSMITTED=`grep $DEVICE /proc/net/dev | awk '{print $10}'`
SPEED=$((($RECEIVED+$TRANSMITTED-$TOTAL)/$SLP))

#echo "Current speed: `human_readable $SPEED`/s"


if ( [ $SPEED -gt $critical ] )
then
    MSG="CRITICAL"
    STATUS=2
else
    if ( [ $SPEED -gt $warning ] )
    then
        MSG="WARNING"
        STATUS=1
    else
        MSG="OK"
        STATUS=0
    fi
fi

#print Message and exit
echo "$MSG - iface $DEVICE `human_readable $SPEED`/s | 'spd'=$SPEED; 'wrn'=$warning; 'crt'=$critical; 'rev'=$RECEIVED; 'tra'=$TRANSMITTED;"
exit $STATUS

icinga / nagios plugin

• prints out one line status (https://docs.icinga.com/latest/de/pluginapi.html) or help