Linux server: Send mail to my users

Question

I am fairly new to creating server scripts and jobs that the server runs every day.

My problem is as follow:

I want to send an email to my users reminding them of a specific job they have to do.

My idea:

Database -> collect all users who needs to be notified and insert them into a table notify_user

Script -> find all users and send them a mail

Script -> Delete all from the table

This script will then run at a specific time every day for instance every 24th hour.

As I stated earlier I am not really keen on how to setup such a script.

My server is an Ubuntu server and my application is a PHP program.

Does anyone know how I might achieve this or know where I might find some documentation on this subject since I have been unable to find anything that solves this issue.

Answer 1

If given that you know how to populate the 'notify_user' table then these are my steps to reproduce a solution sample for you. I did this on my VPS server with sendmail daemon running.

# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 167
Server version: 5.5.40-0ubuntu0.14.04.1 (Ubuntu)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>  create database stack_mail_db;
Query OK, 1 row affec`enter code here`ted (0.05 sec)
mysql> grant all privileges on stack_mail_db.* to 'stack_mail_usr'@'localhost' identified by 'stack_mail_pass';
Query OK, 0 rows affected (0.11 sec)
mysql> use stack_mail_db;
Database changed
mysql> create table notify_user( id int not null auto_increment primary key, user_name tinytext, user_email tinytext );
Query OK, 0 rows affected (0.28 sec)

After creating this sample database we should populate it with at least 2 users (for testing) with working emails. I changed here the actual emails I used.

mysql> insert notify_user (user_name, user_email) values ('test1', '[email protected]');
Query OK, 1 row affected (0.18 sec)

mysql> insert notify_user (user_name, user_email) values ('test2', '[email protected]');
Query OK, 1 row affected (0.03 sec)

Now we should write a script that gets these details and sends emails:

# vim cron_email.php
<?php
$host = 'localhost';
$user = 'stack_mail_usr';
$pass = 'stack_mail_pass';
$dbname = 'stack_mail_db';

$conn = new mysqli($host, $user, $pass, $dbname);

if ($conn->connect_error) {
        trigger_error('DB connection failed: ' . $conn->connect_error, E_USER_ERROR);
}

$query = 'select * from notify_user';

$res = $conn->query($query);

if ($res === false) {
        trigger_error('Failed query: ' . $query . ' Error: ' . $conn->error, E_USER_ERROR);
}

$headers = 'From: [email protected]' . "\r\n" .
        'Reply-To: [email protected]' . "\r\n" .
        'X-Mailer: PHP/' . phpversion();
$res->data_seek(0);
while ($row = $res->fetch_assoc()) {
        $to = $row['user_email'];
        $subject = 'Notification for ' . $row['user_name'];
        $message = 'Hello ' . $row['user_name'];
        $mail = mail($to, $subject, $message, $headers);
        if ($mail) {
                $conn->query('delete from notify_user where id=' . $row['id']);
        } else {
                echo "Email failed\n";
        }
}

Now it's time to put this script on cron:

# crontab -e
0 0 * * * php -f /path/to/cron_email.php

This will run your script exactly every midnight. If you want to set a more specific hour, look at this tutorial: http://www.cyberciti.biz/faq/how-do-i-add-jobs-to-cron-under-linux-or-unix-oses/

Hope this helps ^)