Too automate data backups to another directory, it's crucial to verify if rsync is already runing before initiating a new backup. This prevents multiple rsync processes from overloading the server, which can cause performance issues or crashes.

Setting Up SSH Key Authentication to Passwrodless rsync

1. Generate an SSH key pair on the source server:

   ssh-keygen
   

   Press Enter to accept default settings.

2. Copy the public key to the remote backup server:

   ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.1.100
   

   Enter the remote server password when prompted.

Configuring Cron for Scheduled Backups

Add a cron job to run the backup script every 5 minutes:

crontab -l
*/5 * * * * bash /usr/local/mail/backrsync.sh

Backup Script with Process Checking

Create a script that checks for eixsting rsync processes before executing backups:

#!/bin/bash
# Script: backup_script.sh

LOG_FILE="/var/log/backup_log"
CURRENT_TIME=$(date "+%Y-%m-%d %H:%M:%S")

log_message() {
    local print_to_console=$1
    local message="$CURRENT_TIME $2"
    if [ $print_to_console -eq 1 ]; then
        echo "$message"
    fi
    echo "$message" >> "$LOG_FILE"
}

validate_command() {
    local exit_code=$?
    if [ $exit_code -ne 0 ]; then
        log_message 1 "#[ERROR] Command failed: $1"
        exit 1
    fi
}

log_message 1 "Backup process initiated"

# Check for existing rsync processes
ps -ef | grep 'rsync' | grep -v 'grep' | grep -v 'backup_script'
if [ $? -ne 0 ]; then
    log_message 1 "Starting backup..."
    log_message 0 "Cron job triggered at $CURRENT_TIME"
    
    backup_target="/umaildataback/backup"
    if [ -d "$backup_target" ]; then
        /usr/bin/rsync -rav /home/mailbox "$backup_target/"
        validate_command "rsync /home/mailbox"
        
        /usr/bin/rsync -rav /usr/local/mail/data/mailbox /mailbackmailbox/
        validate_command "rsync /usr/local/mail/data/mailbox"
        
        /usr/bin/rsync -rav /usr/local/mail/data/backup/ /mailbackmailbox/mysqlback/
        validate_command "rsync /usr/local/mail/data/backup"
        
        log_message 0 "Backup completed successfully"
    else
        log_message 1 "Backup directory $backup_target not found"
    fi
else
    log_message 1 "rsync already running, skipping this cycle"
    log_message 0 "$CURRENT_TIME: Process already active"
fi

log_message 1 "Backup process completed"

Restarting the Cron Service

After setting up the script, restart the cron service to apply changes:

/etc/init.d/crond restart