10 Corporate Real-Time Shell Scripts

Backup Script Script

SOURCE="/home/ubuntu/Test01"
DESTINATION="/home/ubuntu/Test02/"
DATE=$(date +%Y-%m-%d_%H-%M-%S)

# Create backup directory and copy files

mkdir -p $DESTINATION/$DATE
cp -r $SOURCE $DESTINATION/$DATE
echo "Backup completed on $DATE"

Explanation

• SOURCE: The directory to be backed up. • DESTINATION: The directory where the backup will be stored. • DATE: Captures the current date and time to create a unique backup folder.

• mkdir -p $DESTINATION/$DATE: Creates the backup directory if it does not exist.

• cp -r $SOURCE $DESTINATION/$DATE: Copies the contents of the source directory to the backup directory.

• echo "Backup completed on $DATE": Outputs a message indicating the completion of the backup.

Scheduling the backup with Cron

To schedule regular execution of the backup script, utilize the crontab editor by running the following command:

crontab -e

Once in the editor, add the following line to configure the backup schedule:

text* * * * * /path/to/backup_script.sh

This configuration will execute the backup script every minute5. Modify the cron schedule parameters to align with your desired backup frequency.

Disk Usage Monitoring Script

Script Overview

This Bash script monitors disk usage across partitions and issues warnings when usage exceeds a predefined threshold.

bash#!/bin/bash

THRESHOLD=80

df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
    usage=$(echo $output | awk '{ print $1}' | cut -d'%' -f1)
    partition=$(echo $output | awk '{ print $2 }')
    if [ $usage -ge $THRESHOLD ]; then
        echo "Warning: Disk usage on $partition is at ${usage}%"
    fi
done

Functionality Breakdown

1. Threshold Setting: The script initializes with a disk usage threshold of 80%.

2. Disk Usage Data Collection: Utilizes df -H to retrieve disk usage information in a human-readable format.

3. Data Filtering: Employs grep to exclude non-essential filesystem entries.

4. Data Extraction: Uses awk to isolate usage percentages and partition names.

5. Iterative Processing: Processes each filtered entry using a while loop.

6. Usage Calculation: Extracts the numerical usage percentage from each entry.

7. Partition Identification: Isolates the partition name for each entry.

8. Threshold Comparison: Compares the usage against the predefined threshold.

9. Alert Generation: Outputs a warning message for partitions exceeding the threshold.

Service Health Check

This script checks if a specified service is running and starts it if not.

bash#!/bin/bash

SERVICE="nginx"

if systemctl is-active --quiet $SERVICE; then
    echo "$SERVICE is running"
else
    echo "$SERVICE is not running"
    systemctl start $SERVICE
fi

Explanation:

• SERVICE: Specifies the name of the service to check (nginx in this example).

• systemctl is-active --quiet $SERVICE: Checks if the service is running.

• If the service is running, it prints a confirmation message.

• If it is not running, it prints a message and attempts to start the service.

Network Connectivity Check

This script checks network connectivity to a specified host.

bash#!/bin/bash

HOST="google.com"
OUTPUT_FILE="/home/ubuntu/output.txt"

if ping -c 1 $HOST &> /dev/null
then
    echo "$HOST is reachable" >> $OUTPUT_FILE
else
    echo "$HOST is not reachable" >> $OUTPUT_FILE
fi

Explanation:

• HOST: Specifies the hostname to check.

• OUTPUT_FILE: Defines where to write the output.

• ping -c 1 $HOST &> /dev/null: Pings the host once, suppressing output.

• Depending on the ping result, it writes a reachability status to the output file.

Database Backup

This script creates a backup of a specified MySQL database.

bash#!/bin/bash

DB_NAME="mydatabase"
BACKUP_DIR="/path/to/backup"
DATE=$(date +%Y-%m-%d_%H-%M-%S)

mysqldump -u root -p $DB_NAME > $BACKUP_DIR/$DB_NAME-$DATE.sql

echo "Database backup completed: $BACKUP_DIR/$DB_NAME-$DATE.sql"

Explanation:

• DB_NAME: Specifies the database to back up.

• BACKUP_DIR: Defines where to store the backup.

• DATE: Captures the current date and time for a unique filename.

• mysqldump command creates a SQL dump of the database.

• The echo statement confirms the backup completion and location.

System Uptime Check

This simple script displays the system's uptime.

bash#!/bin/bash

uptime -p

Explanation:

• uptime -p: Prints the system uptime in a human-readable format.

Listening Ports Monitor

This script lists all listening ports and their associated services.

bash#!/bin/bash

netstat -tuln | grep LISTEN

Explanation:

• netstat -tuln: Lists all TCP and UDP listening ports.

• grep LISTEN: Filters the output to show only listening ports.

Automatic Package Updates

This script updates and cleans up system packages.

bash#!/bin/bash

apt-get update && apt-get upgrade -y && apt-get autoremove -y && apt-get clean
echo "System packages updated and cleaned up"

Explanation:

• apt-get update: Updates the package list.

• apt-get upgrade -y: Upgrades all installed packages.

• apt-get autoremove -y: Removes unnecessary packages.

• apt-get clean: Cleans up the package cache.

• The echo statement confirms the completion of updates and cleanup.

HTTP Response Time Monitor

This script checks HTTP response times for specified URLs.

bash#!/bin/bash

URLS=("https://www.devopsshack.com/" "https://www.linkedin.com/")

for URL in "${URLS[@]}"; do
    RESPONSE_TIME=$(curl -o /dev/null -s -w '%{time_total}\n' $URL)
    echo "Response time for $URL: $RESPONSE_TIME seconds"
done

Explanation:

• URLS: An array of URLs to check.

• The for loop iterates over each URL.

• curl command fetches each URL and measures the total response time.

• The script prints the response time for each URL.

System Process and Memory Usage Monitor

This script displays the top processes by memory usage.

bash#!/bin/bash

ps aux --sort=-%mem | head -n 10

Explanation:

• ps aux: Lists all running processes.

• --sort=-%mem: Sorts processes by memory usage in descending order.

• head -n 10: Displays only the top 10 processes.

These scripts provide valuable tools for various DevOps tasks, from system monitoring to backup and maintenance operations.