Essential Shell Scripts for Linux Ops: Alerts, MySQL Backup, and Traffic Monitoring

Shell scripting is a fundamental tool for Linux system administrators, enabling automation of repetitive tasks such as sending alerts, backing up databases, and monitoring network traffic. Below are three practical scripts that can be copied directly into your environment.

1. Linux System Alert Script

Configure mailx to send email notifications and create a simple script to trigger alerts.

# yum install mailx
vi /etc/mail.rc
set [email protected] smtp=smtp.163.com
set [email protected]
set smtp-auth-password=123456
set smtp-auth=login

2. MySQL Database Backup Loop

This Bash script iterates over all non‑system databases on a MySQL server, creates a timestamped dump for each, and stores the files in /data/db_backup.

#!/bin/bash
DATE=$(date +%F_%H-%M-%S)
HOST=localhost
USER=backup
PASS=123.com
BACKUP_DIR=/data/db_backup
DB_LIST=$(mysql -h $HOST -u $USER -p$PASS -s -e "show databases;" 2>/dev/null | egrep -v "Database|information_schema|mysql|performance_schema|sys")
for DB in $DB_LIST; do
  BACKUP_NAME=$BACKUP_DIR/${DB}_${DATE}.sql
  if ! mysqldump -h $HOST -u $USER -p$PASS -B $DB > $BACKUP_NAME 2>/dev/null; then
    echo "$BACKUP_NAME backup failed!"
  fi
done

3. Real‑Time Network Interface Traffic Script

Pass the network interface name as the first argument to monitor inbound and outbound traffic in KB/s, updating every second.

#!/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 "%.1fKB/s" $((($NEW_IN-$OLD_IN)/1024)))
  OUT=$(printf "%.1fKB/s" $((($NEW_OUT-$OLD_OUT)/1024)))
  echo "$IN $OUT"
  sleep 1
done

These scripts illustrate core automation techniques for system monitoring and maintenance, and can be adapted to fit specific environments.