Install PowerShell Ubuntu 16.04.5 LTS

This Blog Post Will help you install PowerShell into Ubuntu

PowerShell is a task automation and configuration management framework from Microsoft, consisting of a command-line shell and associated scripting language

run this command one by one

# Import the public repository GPG keys
curl https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -

# Register the Microsoft Ubuntu repository
curl https://packages.microsoft.com/config/ubuntu/14.04/prod.list | sudo tee /etc/apt/sources.list.d/microsoft.list

For Run PowerShell run
$ pwsh