This post describes how you can install Python Pip on ubuntu 18.04.
Why apt doesn’t work immediately
By default the server edition of Ubuntu only includes the main repository for the Ubuntu software. This is for various performance and security reasons but means that there are a number of packages that don’t fit into this realm.
To be able to install pip you will need to configure an additional set of repositories to download it.
Configuring the Universe repositories
As an administrator or by using sudo you will need to edit
/etc/apt/sources.list. This will allow for the list of apt sources to be configured. For example you can run the below command to edit the file.
sudo nano /etc/apt/sources.list
If this is a clean install of Ubuntu 18.04 server this file will likely contain the following lines.
deb http://archive.ubuntu.com/ubuntu bionic main
deb http://archive.ubuntu.com/ubuntu bionic-security main
deb http://archive.ubuntu.com/ubuntu bionic-updates main
To add the universe repositories you need to add
universe to the end of each line. Your modified file should look like the following.
deb http://archive.ubuntu.com/ubuntu bionic main universe
deb http://archive.ubuntu.com/ubuntu bionic-security main universe
deb http://archive.ubuntu.com/ubuntu bionic-updates main universe
Once this has been done, save the file using
Ctrl-O if you are using Nano.
Now you can update apt, and then install python-pip.
sudo apt update
sudo apt install python-pip
In addition to pip, this will allow installation of many other packages.