#!/bin/bash

MAXIMUM_BACKUP_FILES=10              #最大备份文件数
BACKUP_FOLDERNAME="/var/db/backup/"  #数据库备份文件的主目录
DB_HOSTNAME="localhost"              #mysql所在主机的主机名
DB_USERNAME="backupaccount"                   #mysql登录用户名
DB_PASSWORD="backuppassword"                 #mysql登录密码
DATABASES=(
            "dbname"                    #备份的数据库名
)
#=========
echo "Bash Database Backup Tool"
#CURRENT_DATE=$(date +%F)
CURRENT_DATE=$(date +%F)              #定义当前日期为变量
cd "$BACKUP_FOLDERNAME"
TMP_FOLDER="${CURRENT_DATE}" #存放数据库备份文件的目录
mkdir "$TMP_FOLDER" #创建数据库备份文件目录
#统计需要被备份的数据库
count=0
while [ "x${DATABASES[count]}" != "x" ];do
    count=$(( count + 1 ))
done
echo "[+] ${count} databases will be backuped..."
#循环这个数据库名称列表然后逐个备份这些数据库
for DATABASE in ${DATABASES[@]};do
    echo "[+] Mysql-Dumping: ${DATABASE}"
    echo -n "   Began:  ";echo $(date)
    if $(mysqldump -h ${DB_HOSTNAME} -u${DB_USERNAME} -p${DB_PASSWORD} ${DATABASE} > "${TMP_FOLDER}/${DATABASE}.sql");then
        echo "  Dumped successfully!"
    else
        echo "  Failed dumping this database!"
    fi
    echo -n "   Finished: ";echo $(date)
done
echo
echo "[+] Packaging and compressing the backup folder..."
tar -cv "${TMP_FOLDER}" | bzip2 >"${BACKUP_FOLDERNAME}/${CURRENT_DATE}.tar.bz2" && rm -rf "$TMP_FOLDER"
BACKUP_FILES_MADE=$(ls -l ${BACKUP_FOLDERNAME}*.tar.bz2 | wc -l)
BACKUP_FILES_MADE=$(( $BACKUP_FILES_MADE - 0 ))
#把已经完成的备份文件数的结果转换成整数数字

echo
echo "[+] There are ${BACKUP_FILES_MADE} backup files actually."
#判断如果已经完成的备份文件数比最大备份文件数要大，那么用已经备份的文件数减去最大备份文件数,打印要删除旧的备份文件
if [ $BACKUP_FILES_MADE -gt $MAXIMUM_BACKUP_FILES ];then
    REMOVE_FILES=$(( $BACKUP_FILES_MADE - $MAXIMUM_BACKUP_FILES ))
    echo "[+] Remove ${REMOVE_FILES} old backup files."
    #统计所有备份文件，把最新备份的文件存放在一个临时文件里，然后删除旧的文件，循环出临时文件的备份文件从临时目录里移到当前目录
    ALL_BACKUP_FILES=($(ls -t ${BACKUP_FOLDERNAME}*.tar.bz2))
    SAFE_BACKUP_FILES=("${ALL_BACKUP_FILES[@]:0:${MAXIMUM_BACKUP_FILES}}")
    echo "[+] Safeting the newest backup files and removing old files..."
    FOLDER_SAFETY="${BACKUP_FOLDERNAME}_safety_{$CURRENT_DATE}"
    if [ ! -d "$FOLDER_SAFETY" ];then
        mkdir "$FOLDER_SAFETY"
    fi;
    for FILE in ${SAFE_BACKUP_FILES[@]};do
        echo $FILE
        mv -i "${FILE}" "${FOLDER_SAFETY}"
    done
    rm -rf ${BACKUP_FOLDERNAME}*.tar.bz2
    mv -i ${FOLDER_SAFETY}/* ${BACKUP_FOLDERNAME}
    rm -rf ${FOLDER_SAFETY}
fi;