Amazon recomends using the pip package manager to install its awscli. However we prefer to keep things simple and have all our packages installed with one package manager APT. AWS states the awscli package is available in repositories for other package managers such as APT and yum, but it is not guaranteed to be the latest version unless you get it from pip or use the bundled installer. So use pip if you want the absolute latest, but APT is fine otherwise.
Installing Using APT
sudo apt-get install awscli