Bash Scripts for Real‑Time Network Traffic and Disk Usage Monitoring

This article presents two practical Bash scripts for system monitoring.

Script 1 – Real‑time network traffic monitoring

The script accepts a network interface name as an argument and continuously prints the inbound and outbound traffic rates in KB/s.

#!/bin/bash
NIC=$1
echo -e " In ------ Out"
while true; do
  OLD_IN=$(awk '$0~"'$NIC'"{print $2}' /proc/net/dev)
  OLD_OUT=$(awk '$0~"'$NIC'"{print $10}' /proc/net/dev)
  sleep 1
  NEW_IN=$(awk '$0~"'$NIC'"{print $2}' /proc/net/dev)
  NEW_OUT=$(awk '$0~"'$NIC'"{print $10}' /proc/net/dev)
  IN=$(printf "%.1f%s" "$((($NEW_IN-$OLD_IN)/1024))" "KB/s")
  OUT=$(printf "%.1f%s" "$((($NEW_OUT-$OLD_OUT)/1024))" "KB/s")
  echo "$IN $OUT"
  sleep 1
done

Script 2 – Disk usage monitoring for 100 servers

This script reads a host list file (host.info) containing IP, username, and SSH port, connects to each server, retrieves disk usage via df -h, and warns if any partition usage exceeds 80%.

#!/bin/bash
HOST_INFO=host.info
for IP in $(awk '/^[^#]/{print $1}' $HOST_INFO); do
  USER=$(awk -v ip=$IP 'ip==$1{print $2}' $HOST_INFO)
  PORT=$(awk -v ip=$IP 'ip==$1{print $3}' $HOST_INFO)
  TMP_FILE=/tmp/disk.tmp
  ssh -p $PORT $USER@$IP 'df -h' > $TMP_FILE
  USE_RATE_LIST=$(awk 'BEGIN{OFS="="}/^\/dev/{print $NF,int($5)}' $TMP_FILE)
  for USE_RATE in $USE_RATE_LIST; do
    PART_NAME=${USE_RATE%=*}
    USE_RATE=${USE_RATE#*=}
    if [ $USE_RATE -ge 80 ]; then
      echo "Warning: $PART_NAME Partition usage $USE_RATE%!"
    fi
  done
done

The article concludes with a list of related reading links for further exploration of monitoring, DevOps, and shell scripting topics.