Tag: mysql

MySQL Backup To S3 Bucket

Here’s my MySQL backup script to the S3 Bucket.

Just a couple of things about the script. It’s using …

  1. AWS CLI
  2. Mysqldump

They must be setup and configured to work properly.

#!/bin/bash
cd /root/database
TIMESTAMP=$(date +%Y-%m-%d)
S3FILE="s3://bucketname/sqlbackup/backup-$TIMESTAMP.sql"
/usr/bin/mysqldump dbname > dbname.sql
/usr/local/bin/aws s3 cp dbname.sql $S3FILE
sleep 3s
rm dbname.sql

Finally, set the S3 bucket with a 7 day retention. Backups older than 7 days are automatically deleted.

Recover MySQL Root Password

How to recover a MySQL root password without a password.

  1. Stop MySQL.
  2. Start MySQL Safe Mode.
  3. Login to MySQL as root without password.
  4. Change root password.

# Stop MySQL.
service mysql stop
# MySQL Safe Mode.
mysqld_safe --skip-grant-tables &
# Login to MySQL without password. Set new password.
mysql -u root -p
use mysql;
# For MySQL 5.6 or lower
UPDATE mysql.user SET Password=PASSWORD('newpassword') WHERE User='root';
# For MySQL 5.7 or higher
SET PASSWORD FOR 'root'@'localhost' = PASSWORD("newpassword");
FLUSH PRIVILEGES;
exit;
# Kill mysqld
killall mysqld
# Restart MySQL
service mysql start

I ran into issues running MySQL Safe mode. I got a “UNIX socket file don’t exists” error. Here’s the fix.

mkdir -p /var/run/mysqld
chown mysql:mysql /var/run/mysqld

Run SQL in Bash

Here’s an example on how to run MySQL commands from Bash.

mysql dbname -e "UPDATE wp_options SET option_value='http://domain.com' WHERE option_name='home'";
mysql dbname -e "UPDATE wp_options SET option_value='http://domain.com' WHERE option_name='siteurl'";

The example updates WordPress’ home and siteurl. Script contains no password. It’s using .my.cnf config file.

Quick Database Check

Here’s a quick PHP script to check if your web server can connect to your MySQL database. It’s a neat little script if you don’t have any application installed yet, and you just want to see if your web server setup can quickly connect to the database. All you have to do is create a new file called connect.php, and place the following code inside. Just change the username, password and database. Most likely the hostname will be localhost.

$ sudo nano /var/www/html/connect.php
$username = "user";
$password = "password";
$hostname = "hostname";
$database = "database";
 
$dbhandle = mysql_connect($hostname, $username, $password) or die("Unable to connect to MySQL");
echo "Successfully Connected to the MySQL Database.<br/>";
 
$selected = mysql_select_db("$dbname", $dbhandle) or die("Could not select database");
echo "Successfully Connected to Database called: $database";

It’s also available on my Github gist.

Where Featured Images Are Stored

The WordPress Genesis theme uses featured images on its posts on several of its themes. If you’re curious as to where the Genesis theme stores the image links on the database, you’ll need to go to a couple of WordPress tables to find them. First and foremost, you’ll need to get the ID of your WordPress post. You can easily find this by hovering over the edit link and checking the ID number.

Let’s pretend the post ID is 110. You will then need to find the meta_value in the wp_postmeta table.

Table: wp_postmeta

meta_id     post_id   meta_key         meta_value
544         110       _thumbnail_id    45
SELECT meta_value FROM wp_postmeta WHERE meta_key='_thumbnail_id' and post_id=110;

The result is 45. Now that you have the meta_value, you can then search for the link from the wp_posts table.

Table: wp_posts

ID      post_type       guid
45      attachment      http://yourdomain.com/wp-content/uploads/2017/03/featured-image.jpg
SELECT guid FROM wp_posts WHERE post_type='attachment' and id=45;

The result will be the URL of the image, e.g. http://yourdomain.com/wp-content/uploads/2017/03/featured-image.jpg.

It’s an odd place to store the image link, but that’s where it is.