Essential Production Shell Scripts: MySQL Backup, Nginx Monitoring & System Init

Production environments often rely on various shell scripts; this article presents several commonly used scripts for enterprise Linux servers.

1. MySQL Full Backup and Remote Sync Script

This Bash script performs a full MySQL dump for listed databases, compresses the output, logs the operation, synchronizes the backup to a remote server via rsync, and removes backups older than 30 days.

#!/bin/bash
# description: MySQL backup shell script
# author: magedu.com
# 192.168.10.10 is the backup server; set up passwordless SSH

DATABASES=(
    "magedu01"
    "magedu02"
)
USER="root"
PASSWORD="dbpwd123"
MAIL="[email protected]"
BACKUP_DIR=/data/backup
LOGFILE=/data/backup/data_backup.log
DATE=`date +%Y%m%d_%H%M`

cd $BACKUP_DIR
echo "--------------------" >> $LOGFILE
echo "BACKUP DATE:" $(date +"%y-%m-%d %H:%M:%S") >> $LOGFILE
echo "-------------------" >> $LOGFILE

for DATABASE in ${DATABASES}; do
    /usr/local/mysql/bin/mysqldump -u$USER -p$PASSWORD --events -R --opt $DATABASE | gzip > ${BACKUP_DIR}/${DATABASE}_${DATE}.sql.gz
    if [ $? == 0 ]; then
        echo "$DATE--$DATABASE is backup succeed" >> $LOGFILE
    else
        echo "Database Backup Fail!" >> $LOGFILE
    fi
done

if [ $? == 0 ]; then
    /usr/bin/rsync -zrtopg --delete /data/backup/* [email protected]:/data/backup/ > /dev/null 2>&1
else
    echo "Database Backup Fail!" >> $LOGFILE
    mail -s "database Daily Backup Fail!" $MAIL
fi

# Delete backups older than 30 days
find $BACKUP_DIR -type f -mtime +30 -name "*.gz" -exec rm -f {} \;

2. Nginx Process Monitoring and Keepalived Switch Script

This script checks the Nginx process every five seconds; if Nginx is not running, it restarts Nginx and stops Keepalived to trigger VIP failover.

#!/bin/bash
while :
do
    nginxpid='ps -C nginx --no-header | wc -l'
    if [ $nginxpid -eq 0 ]; then
        ulimit -SHn 65535
        /usr/local/nginx/sbin/nginx
        sleep 5
        nginxpid='ps -C nginx --no-header | wc -l'
        if [ $nginxpid -eq 0 ]; then
            /etc/init.d/keepalived stop
        fi
    fi
    sleep 5
done

3. MySQL Slave Status Monitoring and Alert Script

The script verifies that MySQL is listening on port 3306, checks that both the slave IO and SQL threads report “Yes”, and sends email alerts when conditions are not met; it is intended to run via cron every ten minutes.

#!/bin/bash
MYSQLPORT='netstat -na|grep "LISTEN"|grep "3306"|awk -F[:" "]+ {print $4}'
MYSQLIP='ifconfig eth0|grep "inet addr" | awk -F[:" "]+ {print $4}'
STATUS=$(/usr/local/mysql/bin/mysql -u dbuser -pdbpwd123 -S /tmp/mysql.sock -e "show slave status\G" | grep -i "running")
IO_env='echo $STATUS | grep IO | awk {print $2}'
SQL_env='echo $STATUS | grep SQL | awk {print $2}'

if [ "$MYSQLPORT" == "3306" ]; then
    echo "mysql is running"
else
    mail -s "warn! server: $MYSQLIP mysql is down" [email protected]
fi

if [ "$IO_env" = "Yes" -a "$SQL_env" = "Yes" ]; then
    echo "Slave is running!"
else
    echo "####### $date #########" >> /data/log/check_mysql_slave.log
    echo "Slave is not running!" >> /data/log/check_mysql_slave.log
    mail -s "warn! $MySQLIP_replicate_error" [email protected] < /data/log/check_mysql_slave.log
fi

# Suggested cron entry (run every 10 minutes)
# */10 * * * * root /bin/sh /root/check_mysql_slave.sh

4. CentOS 7 System Initialization Script

This comprehensive script prepares a newly installed CentOS 7 server: it replaces the default YUM repository, installs NTP, disables firewalld and SELinux, installs common tools, and upgrades the kernel to the latest mainline version.

#!/bin/bash
# Filename: centos7-init.sh
# Author: [email protected]

if [ `whoami` != "root" ]; then
    echo "only root can run it"
    exit 1
fi

echo -e "\033[31m This is the centos7 system initialization script, it will update the kernel to the latest version, proceed with caution! \033[0m"
read -s -n1 -p "Press any key to continue or ctrl+C to cancel"
echo "Your inputs: $REPLY"

yum_config() {
    mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
    wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
    yum clean all && yum makecache
}

ntp_config() {
    yum -y install chrony
    systemctl start chronyd && systemctl enable chronyd
    timedatectl set-timezone Asia/Shanghai && timedatectl set-ntp yes
}

close_firewalld() {
    systemctl stop firewalld.service &>/dev/null
    systemctl disable firewalld.service &>/dev/null
}

close_selinux() {
    setenforce 0
    sed -i 's/enforcing/disabled/g' /etc/selinux/config
}

yum_tools() {
    yum install -y vim wget curl curl-devel bash-completion lsof iotop iostat unzip bzip2 bzip2-devel
    yum install -y gcc gcc-c++ make cmake autoconf openssl-devel openssl-perl net-tools
    source /usr/share/bash-completion/bash_completion
}

update_kernel() {
    rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
    rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
    yum --enablerepo=elrepo-kernel install -y kernel-ml
    grub2-set-default 0
    grub2-mkconfig -o /boot/grub2/grub.cfg
}

main() {
    yum_config
    ntp_config
    close_firewalld
    close_selinux
    yum_tools
    update_kernel
}
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