Script Overview

This script is designed to install the latest PowerShell 7 on a fresh Windows 11 system, including pre-OOBE deployments (before the first user login). It is fully offline-safe, automated, and cleans up after itself.

It is ideal for IT departments, system imaging, automated deployments, or lab setups where you want a consistent PowerShell 7 environment without manual intervention.

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High-Level Features

1.	Self-bypasses PowerShell execution policy so it can run on systems where script execution is restricted.

2.	Detects Internet connectivity and chooses whether to download the latest MSI or use a cached MSI file in %TEMP%.

3.	Deletes old cached MSI files if outdated.

4.	Cleans old PowerShell 7 installations to ensure a fresh install.

5.	Removes temp files, module caches, and MSI logs to prevent leftover clutter.

6.	Performs silent installation of PowerShell 7 using msiexec.

7.	Verifies installation by checking the installed PowerShell 7 version.

8.	Provides a console-only summary of actions taken and the installed version.

9.	Cleans the PowerShell session at the end (variables, functions, aliases, history, console), leaving a clean environment.

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Step-by-Step Behavior

1. Execution Policy Self-Bypass

   • On systems where script execution is restricted, the script relaunches itself with -ExecutionPolicy Bypass.

   • This ensures it can run pre-OOBE or on locked-down environments without permanently changing the system policy.

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2. Internet and Cached MSI Check

   • Checks if the system has Internet access by attempting a quick request to https://github.com.

   • Checks %TEMP% for an existing PowerShell 7 MSI file.

   • Handles all scenarios:

   1. Internet + no cached MSI → downloads the latest MSI.

   2. Internet + cached MSI exists → compares version:

   • If cached MSI is older, deletes and downloads the latest.

   • If cached MSI is up-to-date, uses it.

   3. No Internet + cached MSI exists → uses cached MSI.

   4. No Internet + no cached MSI → displays Check Internet, waits 3 seconds, and exits.

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3. Clean Old PowerShell 7 Installations

   • Detects previous PS7 installations in C:\Program Files\PowerShell\7*.

   • Deletes old folders recursively to prevent conflicts with the new installation.

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4. Clear Module Caches and Temp Logs

   • Deletes user-level PowerShell module caches at %LOCALAPPDATA%\Microsoft\PowerShell.

   • Deletes system-level modules at %ProgramData%\Microsoft\PowerShell\Modules.

   • Removes temporary MSI log files in %TEMP%.

This prevents old or conflicting modules, logs, or temp files from interfering with the new installation.

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5. Silent Installation of PowerShell 7

   • Uses msiexec.exe /i /qn /norestart to install silently without user interaction.

   • Deletes the downloaded MSI afterward to save space.

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6. Installation Verification

   • After installation, the script checks the installed PowerShell version using $PSVersionTable.PSVersion.

   • This ensures that the intended version was successfully installed.

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7. Console Summary

At the end, the script prints a clear plain-text summary:

Action Taken: Shows what the script did: used cached MSI, deleted old MSI, downloaded new MSI, etc.

Installed Version: Displays the PowerShell 7 version installed, or Failed if installation did not succeed.

No files are written, and no emojis or extra output are displayed.

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8. Final Session Cleanup

   • Removes all variables, functions, aliases, and command history created during script execution.

   • Clears the PowerShell console (Clear-Host).

   • After this, the session is completely clean, leaving only the newly installed PowerShell 7 environment.

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Key Advantages

1.	Pre-OOBE Ready: Runs before any user logs in.

2.	Offline-Safe: Can install from cached MSI if no Internet is available.

3.	Always Up-to-Date: Automatically downloads latest release if available.

4.	Clean Environment: Removes old installations, temp files, module caches, and leaves no trace in the session.

5.	Silent & Automated: No user interaction required; suitable for bulk deployment.

6.	Console Summary Only: Easy to read for deployment logs without creating extra files.

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Intended Use Cases

•	Corporate imaging or deployment scripts for new Windows 11 machines.

•	Pre-OOBE customization for OEM or IT provisioning.

•	Ensuring consistent PowerShell 7 versions across labs or test environments.

•	Automated setup in WinPE, unattend scripts, or first-boot tasks.