Change phpMyAdmin port from 80 to another number

phpmyadmin.conf

Listen 8081

<VirtualHost *:8081>

        ServerName localhost

        <Directory /usr/share/phpmyadmin>
                AllowOverride None
                Require all granted
        </Directory>

        DocumentRoot /usr/share/phpmyadmin

        Include /etc/phpmyadmin/apache.conf

        ErrorLog ${APACHE_LOG_DIR}/phpmyadmin.error.log
        CustomLog ${APACHE_LOG_DIR}/phpmyadmin.access.log combined

</VirtualHost>

phpmyadmin.sh

# By default PhpMyAdmin is included into the Apache's configuration through this additional configuration file:
# /etc/apache2/conf-enabled/phpmyadmin.conf
# This file is a symbolic link to the file:
# /etc/apache2/conf-available/phpmyadmin.conf
# Which is a symbolic link to the file:
# /etc/phpmyadmin/apache.conf

# Create new VirtualHost configuration file:

sudo nano /etc/apache2/sites-available/phpmyadmin.conf

# disable the default phpMyAdmin's configuration
sudo a2disconf phpmyadmin
# enable the new VirtualHost
sudo a2ensite phpmyadmin
# restart apache
sudo systemctl restart apache2.service

# This step is optional, but otherwise http://localhost:8081 and http://localhost:8081/phpmyadmin will provide identical result
sed -e '/Alias \/phpmyadmin \/usr\/share\/phpmyadmin/ s/^#*/#/' -i /etc/phpmyadmin/apache.conf

# Add port 99 into firewall's rules.
# If you use UFW you can do that by this command:
sudo ufw allow 8081/tcp
# With iptables you can do that by this command:
sudo iptables -A INPUT -p tcp -m tcp --dport 8081 -j ACCEPT