本教學將使用純 php 去備份資料庫並下載到目錄底下

$ crontab -e

設定每天凌晨00:00 執行

0 0 * * * php /var/www/backup.php

backup.php 腳本記得開頭一定要 「<?php」，即便你有啟用縮寫

header('Content-Type: text/html; charset=utf-8');
function backup_mysql_database($options){
$mtables = array(); $contents = "-- Database: `".$options['db_to_backup']."` --\n";

$mysqli = new mysqli($options['db_host'], $options['db_uname'], $options['db_password'], $options['db_to_backup']);
if ($mysqli->connect_error) {
    die('Error : ('. $mysqli->connect_errno .') '. $mysqli->connect_error);
}
$mysqli->query("SET NAMES utf8");
$mysqli->set_charset("utf8mb4");
$results = $mysqli->query("SHOW TABLES");

while ($row = $results->fetch_array()){
    if (!in_array($row[0], $options['db_exclude_tables'])){
        $mtables[] = $row[0];
    }
}

foreach($mtables as $table){
    $contents .= "-- Table `".$table."` --\n";

    $results = $mysqli->query("SHOW CREATE TABLE ".$table);
    while ($row = $results->fetch_array()){
        $contents .= $row[1].";\n\n";
    }

    $results = $mysqli->query("SELECT * FROM ".$table);
    $row_count = $results->num_rows;
    $fields = $results->fetch_fields();
    $fields_count = count($fields);

    $insert_head = "INSERT INTO `".$table."` (";
    for($i=0; $i < $fields_count; $i++){
        $insert_head  .= "`".$fields[$i]->name."`";
            if($i < $fields_count-1){
                    $insert_head  .= ', ';
                }
    }
    $insert_head .=  ")";
    $insert_head .= " VALUES\n";

    if($row_count>0){
        $r = 0;
        while ($row = $results->fetch_array()){
            if(($r % 400)  == 0){
                $contents .= $insert_head;
            }
            $contents .= "(";
            for($i=0; $i < $fields_count; $i++){
                $row_content =  str_replace("\n","\\n",$mysqli->real_escape_string($row[$i]));

                switch($fields[$i]->type){
                    case 8: case 3:
                        $contents .=  $row_content;
                        break;
                    default:
                        $contents .= "'". $row_content ."'";
                }
                if($i < $fields_count-1){
                        $contents  .= ', ';
                    }
            }
            if(($r+1) == $row_count || ($r % 400) == 399){
                $contents .= ");\n\n";
             } else {
                $contents .= "),\n";
            }
            $r++;
        }
    }
}

if (!is_dir ( $options['db_backup_path'] )) {
        mkdir ( $options['db_backup_path'], 0777, true );
 }

## 備份後的 sql 名稱
$backup_file_name = "dev-" . date( "Y-m-d H:i:s").".sql";

$fp = fopen($options['db_backup_path'] . '/' . $backup_file_name ,'w+');
if (($result = fwrite($fp, $contents))) {
   //  echo "Backup file created '$backup_file_name' ($result)";

}
fclose($fp);
return $backup_file_name;
}

## 資料庫設定
$options = array(
    'db_host'=> 'localhost', 
    'db_uname' => 'root', // 資料庫使用者帳號
    'db_password' => 'password', // 資料庫密碼
    'db_to_backup' => 'db', // 資料庫名稱
    'db_backup_path' => '/var/www/', // 保存到哪個路徑
    'db_exclude_tables' => array() 
);
$backup_file_name=backup_mysql_database($options);

這樣就可以透過 php 備份到該主機下，直接產生 sql 檔了。

參考
https://ianakaberlin.medium.com/php-crontab-%E4%BD%BF%E7%94%A8-php-%E9%80%8F%E9%81%8E-crontab-%E6%8E%92%E7%A8%8B%E5%9B%BA%E5%AE%9A%E6%99%82%E9%96%93%E5%82%99%E4%BB%BD-mariadb-mysql-crontab-mysql-mariadb-%E4%BC%8A%E6%81%A9%E8%B8%A9%E5%9D%91%E7%AD%86%E8%A8%98-8c4ba1064e9b