pwsh vs Windows PowerShell 5.1: When “Just Install 7” Isn’t Allowed

The prevailing advice on the internet is to install PowerShell 7, provided you have control over the system. However, this recommendation does not always apply in corporate environments, customer settings, or educational contexts where Windows PowerShell 5.1 is the baseline and pwsh is a feature request awaiting prioritization. The headline differences that have immediate day-to-day implications are as follows:

1. **Shipping Method**: Windows PowerShell 5.1 comes pre-installed on Windows machines, whereas PowerShell 7 requires a separate installation.

2. **Runtime Environment**: PowerShell 7 runs on the .NET Core runtime, supporting .NET 5 and later versions, while 5.1 uses the .NET Framework, which is more common on older Windows systems.

3. **Cross-platform Capability**: PowerShell 7 is designed to run on Windows, macOS, and Linux, making it cross-platform. In contrast, Windows PowerShell 5.1 is limited to the Windows operating system.

4. **Default Encoding**: PowerShell 7 adopts UTF-8 encoding by default, offering better handling of various character sets compared to the defaults found in Windows PowerShell 5.1, which can lead to encoding surprises.

5. **Syntax Features**: PowerShell 7 introduces modern syntax improvements such as the -Parallel parameter for loops, ternary operators, and null-coalescing operators, which are either limited in 5.1 or require different syntax.

6. **Module Compatibility**: The PowerShell 7 module repository includes a broad range of modules, incorporating both Windows-specific and cross-platform modules. However, this variety requires careful handling to ensure compatibility when deploying modules to 5.1 environments.

7. **Remoting and WinRM**: While Windows PowerShell 5.1 is battle-tested in enterprise settings for remote management using Remote Management (WinRM) protocols, PowerShell 7 is newer and may require validation in various enterprise setups.

8. **GPO and Golden Image Constraints**: Group Policy Objects (GPOs) and golden image configurations often still reference the Windows PowerShell 5.1 environment, meaning that changes to the PowerShell version may necessitate updates to these configurations.

9. **Teaching Considerations**: When designing educational materials, it's crucial to distinguish between the two PowerShell versions. While PowerShell 7 is praised for its modern features, teaching only 7-only syntax to students who may primarily be using 5.1 can be counterproductive. Instead, a balanced approach is recommended, highlighting common concepts while explicitly noting version-specific features with visual indicators.