PowerShell is the cornerstone of modern Windows administration and a powerful tool in any cross-platform environment. But before you can leverage its capabilities, you need to get it installed—and that process can vary dramatically depending on your operating system and network connectivity. This definitive guide covers every scenario, from straightforward online installations on Windows and Linux to the specific steps required for air-gapped and secure offline environments. You’ll learn how to install PowerShell itself, as well as how to provision modules and other software in networks without internet access.

Part 1: Installing PowerShell in an Online Environment

If you are still launching the blue icon named “Windows PowerShell”, you are using technology from 2016. pwsh (PowerShell 7+) is the modern, open-source, and cross-platform evolution of PowerShell. It runs on Windows, Linux, and macOS, and it’s the future of PowerShell.

Modern PowerShell runs side-by-side with the older Windows PowerShell, so you can safely install it without breaking legacy scripts.

Installing PowerShell on Windows

Here are the best methods for installing pwsh on Windows 10 and 11.

The Windows Package Manager (winget) is the fastest and most reliable way to install and update PowerShell. On modern versions of Windows, winget is already included.

Open a terminal and run: 

# Search for the package to see available versions
winget search Microsoft.PowerShell

# Install the latest stable version
winget install --id Microsoft.PowerShell --source winget

Alternative Methods for Windows

  • Microsoft Store: Search for “PowerShell” in the Store and click Install. This is great for automatic background updates.
  • Manual MSI Installer: Download the .msi file from the PowerShell GitHub Releases page for offline use or specific version control.

Installing PowerShell on Linux

The best way to install PowerShell on Linux is through your distribution’s native package manager.

On Debian and Ubuntu

  1. Add the Microsoft GPG Signing Key: 
    # Using Ubuntu 22.04 as an example
wget -q "https://packages.microsoft.com/config/ubuntu/22.04/packages-microsoft-prod.deb"
sudo dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb
  2. Update and Install: 
    sudo apt update
sudo apt install -y powershell

On RHEL, CentOS, and Fedora

  1. Register the Microsoft RPM Repository: 
    # Using RHEL 8 as an example
sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc
sudo dnf install -y https://packages.microsoft.com/config/rhel/8/packages-microsoft-prod.rpm
  2. Install: 
    sudo dnf install -y powershell

After installation on any OS, open a new terminal and type pwsh. The prompt should change to PS>. Verify your version with $PSVersionTable.

Part 2: The Guide to Offline Installations

Managing servers in a secure or air-gapped environment presents a unique challenge: how do you install software and modules without an internet connection? The answer is a simple “Download, Transfer, Install” workflow.

Installing PowerShell Modules Offline

If you can’t use Install-Module, you can use an online computer to pre-download the module and its dependencies.

Step 1: Save the Module on an Online Machine

The Save-Module cmdlet is designed for this. On a machine with internet access, create a staging folder and run the command.

# 1. Create a staging directory
$stagingPath = "$env:USERPROFILE\OfflineModules"
New-Item -Path $stagingPath -ItemType Directory -Force

# 2. Save the module (e.g., Posh-SSH) and its dependencies
Save-Module -Name Posh-SSH -Path $stagingPath

Step 2: Transfer the Module Folder

Copy the entire Posh-SSH folder (and any other dependency folders) from your staging directory (C:\Users\YourUser\OfflineModules) to a USB drive.

Step 3: Install the Module on the Offline Machine

On the offline machine, copy the module folders into a location where PowerShell can find them. You can see these locations by running $env:PSModulePath.

  • For the current user: %USERPROFILE%\Documents\PowerShell\Modules
  • For all users (requires admin): %ProgramFiles%\WindowsPowerShell\Modules

Step 4: Verify the Installation

Open a new PowerShell terminal on the offline machine. 

# Check if the module is available
Get-Module -Name Posh-SSH -ListAvailable
# Import the module to start using its commands
Import-Module -Name Posh-SSH

Installing Software & Features Offline (Example: OpenSSH Server)

The same “Download, Transfer, Install” concept applies to Windows features.

Step 1: Obtain the Installer on an Online Machine

  • Method A (Recommended): Download the latest OpenSSH-Win64-vX.X.X.X.msi file from the Win32-OpenSSH GitHub releases page.
  • Method B: Download the Features on Demand (FOD) ISO that matches your Windows build and find the OpenSSH-Server-Package~...~.cab file.

Copy your chosen installer (.msi or .cab) to removable media.

Step 2: Install the Software on the Offline Machine

Transfer the file to the offline machine (e.g., to C:\Temp) and run the appropriate installer from an elevated PowerShell prompt.

  • For the MSI Installer: 
    msiexec /i "C:\Temp\OpenSSH-Win64-v9.5.0.0p1-Beta.msi" /quiet
  • For the CAB File: 
    Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0 -Source C:\Temp

Step 3: Post-Installation and Firewall Configuration

Start the service and open the firewall port. 

# Start the service and set it to start automatically
Start-Service -Name sshd
Set-Service -Name sshd -StartupType Automatic

# Allow inbound traffic on port 22
New-NetFirewallRule -Name "OpenSSH Server (sshd)" -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22

Part 3: Updating PowerShell

Keeping PowerShell up-to-date is just as important as the initial installation. Regular updates provide security patches, performance improvements, and new features.

On Windows

If you installed via winget or the Microsoft Store, updating is simple.

Using winget: 

# See if an update is available
winget list Microsoft.PowerShell
# Upgrade to the latest version
winget upgrade --id Microsoft.PowerShell --source winget

Using the Microsoft Store: Updates are handled automatically by the Microsoft Store app in the background. You can manually check for updates by opening the Store, going to your Library, and clicking “Get updates”.

On Linux

If you used a package manager, updating PowerShell is part of the standard system update process.

On Debian/Ubuntu: 

sudo apt update
sudo apt upgrade powershell

On RHEL/CentOS/Fedora: 

sudo dnf update powershell

By using a package manager for installation, you ensure that keeping PowerShell current is a simple and repeatable process.

Conclusion

Managing PowerShell installations in any environment is straightforward with the right workflow. For online systems, package managers like winget and apt provide the simplest experience. For air-gapped systems, the “Download, Transfer, Install” method using Save-Module and offline installers ensures you can provision any machine, anywhere.