Permanent DNS setup on Ubuntu 18

1. Install the resolvconf package.

   sudo apt install resolvconf

2. Edit /etc/resolvconf/resolv.conf.d/head and add the following:

   # Make edits to /etc/resolvconf/resolv.conf.d/head.
   nameserver 8.8.4.4
   nameserver 8.8.8.8

3. Restart the resolvconf service.

   sudo service resolvconf restart

Ubuntu route configuration

Clear route table: sudo ip route flush table main
Add default route: sudo route add default gw 192.168.1.1
Add route to certain subnet: sudo ip route add 0.0.0.0/0 dev ens33

Add route according to route table: sudo route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.1.1
Add route via: sudo ip route add 192.168.1.0/24 via 192.168.1.1

Delete certain route:
sudo route del -net 192.168.1.0 gw 0.0.0.0 netmask 255.255.255.0
sudo route del -net 192.168.1.0 gw 0.0.0.0 netmask 255.255.255.0 dev ens33

Restart network service:  systemctl restart networking
Restart network manager: sudo service network-manager

To make /etc/network/interfaces effective after changing the file

When changing the file /etc/network/interfaces, there will be no immediate effect except reboot the system. You can run following commands to take effect.

sudo ifconfig ath0 down
sudo /etc/init.d/networking restart
sudo ifconfig ath0 up

Solving Network Manangement Disabled in Ubuntu

go to /etc/NetworkManager/nm-system-settings.conf

then set managed=false to managed=true

sudo service network-manager restart

if there is no change try

touch /etc/NetworkManager/conf.d/10-globally-managed-devices.conf
sudo service network-manager restart

PhpMyAdmin has no export as SQL option problem

Find the Export.php file in the phpmyadmin display folder or something like this phpMyAdmin/libraries/classes/Display depending on type of OS and package.

find the text /* Scan for plugins */ and put the code above right below after the text

if (isset($_GET['single_table'])) { 
$GLOBALS['single_table'] = $_GET['single_table']; 
}

Good luck

Error: Your requirements could not be resolved to an installable set of packages of composer

Solve by putting ignoring platform requirements

Example: composer require --prefer-dist victor78/yii2-zipper:"~0.0.4"

You will get error 

Your requirements could not be resolved to an installable set of packages. Installation failed, reverting ./composer.json to its original content.

So can by as follows: 

composer require --prefer-dist victor78/yii2-zipper:"~0.0.4" --ignore-platform-reqs