Powershell Installation

Windows

Windows comes bundled with Windows Powershell.

Linux

Microsoft provides instructions for several distros, which should work in a pinch. I don't follow them directly, but it's still a good guide.

Debian 11 (Bullseye)

The official instructions say to run the following commands:

# Install system components
sudo apt update  && sudo apt install -y curl gnupg apt-transport-https

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

# Register the Microsoft Product feed
sudo sh -c 'echo "deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-debian-bullseye-prod bullseye main" > /etc/apt/sources.list.d/microsoft.list'

# Install PowerShell
sudo apt update && sudo apt install -y powershell

# Start PowerShell
pwsh

I have a few issues with this: the apt-key command is deprecated, and the apt-transport-https package is now an empty dummy package, and according to the output of apt show apt-transport-https, its functionality has been merged into apt itself. The reason apt-key is deprecated is that it trusts the gpg key to sign all packages, not just those in a particular repo. Because of that, I would do the following:

# Install system components
sudo apt update && sudo apt install -y curl gnupg

# Import the public repository GPG keys
curl https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor | sudo dd of=/etc/apt/keyrings/microsoft.gpg

# Register the Microsoft Product feed
sudo dd of=/etc/apt/sources.list.d/microsoft.list <<EOF
deb [arch=$(dpkg --architecture) signed-by=/etc/apt/keyrings/microsoft.gpg] https://packages.microsoft.com/repos/microsoft-debian-bullseye-prod bullseye main
EOF

# Install PowerShell
sudo apt update && sudo apt install -y powershell

# Start PowerShell
pwsh

This does not rely on deprecated functionality or dummy packages, and has the advantage of only trusting the signing key for packages in the Microsoft apt repository.