To install pip on Ubuntu, Debian or Linux Mint:
$ sudo apt-get install python-pip
To install pip on CentOS, first enable EPEL repository, and then run:
$ sudo yum install python-pip
If you want to install pip3 for python3, you can use the following commands.
$ wget https://bootstrap.pypa.io/get-pip.py
$ sudo python3 get-pip.py
