Tara Prasad Sarangi

Automation Scripts using Bash

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Tara Prasad Sarangi
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Shell script to take backup of var/logfile. Run a cronjob to take backup every monday

Here’s a shell script that takes a backup of /var/logfile, and instructions to set up a cron job to run it every Monday.

Backup Script

  1. Create the Shell Script: Save the following script as backup_logfile.sh:

     #!/bin/bash

 # Define the log file and backup directory
 LOG_FILE="/var/logfile"
 BACKUP_DIR="/var/logfile_backup"

 # Ensure the backup directory exists
 mkdir -p "$BACKUP_DIR"

 # Create a timestamp for the backup file
 TIMESTAMP=$(date +'%Y-%m-%d')
 BACKUP_FILE="$BACKUP_DIR/logfile_backup_$TIMESTAMP.tar.gz"

 # Create a compressed backup of the log file
 tar -czf "$BACKUP_FILE" "$LOG_FILE"

 # Output status
 if [ $? -eq 0 ]; then
     echo "Backup created successfully at $BACKUP_FILE"
 else
     echo "Backup failed"
 fi

    Using [ $? -eq 0 ] is a way to check if the previous command was successful. In this context:

    • This checks if tar -czf "$BACKUP_FILE" "$LOG_FILE" ran without errors ($? -eq 0).

    • If true, it confirms success by outputting "Backup created successfully."

    • If false (meaning a non-zero exit status), it outputs "Backup failed."

This is helpful for providing feedback on whether the backup was created successfully.

  1. Make the Script Executable:

     chmod +x backup_logfile.sh

Setting Up the Cron Job

To run this script every Monday:

  1. Open the crontab editor:

     crontab -e

  2. Add the following line to schedule the script to run every Monday at 12:00 AM:

     0 0 * * 1 /path/to/backup_logfile.sh

    Replace /path/to/backup_logfile.sh with the actual path of your script.

This cron job will execute the backup_logfile.sh script every Monday, creating a new backup with the current date.

Backup S3 Bucket Script

Copies an S3 bucket to a local directory.

#!/bin/bash
BUCKET_NAME="my-s3-bucket"
LOCAL_DIR="/backup/s3"
aws s3 sync s3://$BUCKET_NAME $LOCAL_DIR
echo "Backup of $BUCKET_NAME completed in $LOCAL_DIR."