#!/bin/bash

# 数据库用户名密码（可以考虑使用配置文件或环境变量）
username="root"
password="xxx"

# 历史备份时间文件
history_file="/home/backup/backup_times_history.out"
# 最大备份数量
max_backup_count=5

# mysqldump 命令路径
mysqldump_path="/home/soft/mysql/bin/mysqldump"

# 备份数据库名 列表格式 空格分开
databaseNames=("database1" "database2")

# 备份目录
backup_dir="/home/backup"
dirdate="$(date +% Y% m% d_% H% M% S)"

# 备份开始时间
backup_start_time=$(date +% Y-% m-% d\ % H:% M:% S)

# 创建备份目录
mkdir -p "$backup_dir/$dirdate"

# 备份数据库
for databaseName in "${databaseNames [@]}";
do
    $mysqldump_path -u$username -p$password --single-transaction "$databaseName" | gzip > "$backup_dir/$dirdate/$databaseName.sql.gz"
done

# 备份结束时间
backup_end_time=$(date +% Y-% m-% d\ % H:% M:% S)

# 删除旧备份
if [ -f "$history_file" ]; then
  while [ $(cat "$history_file" | wc -l) -ge $max_backup_count ]; do
    oldest_backup=$(head -n 1 "$history_file")
    rm -rf "$backup_dir/$oldest_backup"
    sed -i '1d' "$history_file"
  done
fi

# 更新备份记录
echo "$dirdate" >> "$history_file"

# 计算备份耗时
backup_duration=$(($(date -d "$backup_end_time" +% s) - $(date -d "$backup_start_time" +% s)))
echo "Backup: $backup_start_time - $backup_end_time, Duration: $backup_duration seconds" >> "$backup_dir/backup.log"