A comprehensive PowerShell script to reliably and cleanly uninstall Cygwin from Windows.

The script automates the manual steps normally required to remove Cygwin, including:

• Stopping and removing Cygwin-related Windows services
• Terminating Cygwin processes
• Deleting Cygwin installation directories and package caches
• Cleaning PATH and CYGWIN environment variables (User + Machine)
• Removing relevant registry keys
• Deleting Cygwin shortcuts from the Desktop and Start Menu

It is designed to be safe, conservative, and idempotent: you can run it multiple times without causing additional damage or unwanted side effects.

The script performs the following actions:

1. Elevation check

   • Verifies that PowerShell is running with Administrator privileges.
   • Exits with an error message if not elevated.

2. Cygwin service cleanup

   • Scans all Windows services using WMI.
   • Identifies services whose PathName contains cygwin (case-insensitive).
   • Attempts to stop each matching service.
   • Removes each matching service with sc.exe delete.

3. Cygwin process termination

   • Attempts to stop common Cygwin-related processes by name:
     • bash, sh, mintty, XWin, xterm, rxvt, cygserver
   • Additionally scans all running processes and terminates any whose executable Path contains cygwin.

4. Detection of Cygwin installation directories

   • Reads from the following registry locations (if present):

     • HKLM:\SOFTWARE\Cygwin\setup
     • HKLM:\SOFTWARE\WOW6432Node\Cygwin\setup
     • HKCU:\Software\Cygwin\setup

   • Uses the rootdir value (when available) to determine the Cygwin installation directory.

   • Also checks standard default install paths:

     • C:\cygwin64
     • C:\cygwin

5. Detection of Cygwin package cache directories

   • Reads the last-cache value (if present) from the same registry keys.
   • Treats these as candidate Cygwin package cache locations.

6. Safe deletion of installation directories

   For each discovered install root:

   • Ensures the path:
     • Exists
     • Is not a drive root (e.g. not C:\)
     • Contains cygwin (case-insensitive) in its path string
   • Takes ownership using takeown.exe.
   • Grants full control to Administrators and the current user via icacls.exe.
   • Deletes the directory recursively with Remove-Item.

7. Safe deletion of package cache directories (optional)

   For each discovered cache directory:

   • Ensures the path:
     • Exists
     • Is not a drive root
     • Contains cygwin in the path
   • Takes ownership and resets permissions (as above).
   • Deletes the directory recursively.

8. Environment variable cleanup

   • For both Machine and User scopes:
     • Retrieves the PATH value.
     • Splits it into entries and removes any that contain cygwin (case-insensitive).
     • Writes back the cleaned PATH value if changes were made.
     • Removes the CYGWIN environment variable if it exists.

9. Registry key cleanup

   Removes the following keys if present:

   • HKLM:\SOFTWARE\Cygwin
   • HKCU:\Software\Cygwin
   • HKLM:\SOFTWARE\WOW6432Node\Cygwin
   • HKCU:\Software\Cygnus Solutions
   • HKLM:\SOFTWARE\Cygnus Solutions
   • HKLM:\SOFTWARE\WOW6432Node\Cygnus Solutions

   These cover both newer Cygwin installs and some older naming (Cygnus Solutions).

10. Shortcut and Start Menu cleanup

    Searches common Desktop and Start Menu locations:

    • Public desktop: %PUBLIC%\Desktop
    • Current user desktop
    • Start Menu (all users): %ProgramData%\Microsoft\Windows\Start Menu\Programs
    • Start Menu (current user): %APPDATA%\Microsoft\Windows\Start Menu\Programs

    For each location:

    • Deletes any shortcuts matching:
      • Cygwin*.lnk
      • Cygwin*Terminal*.lnk
    • Removes any subfolders whose name starts with Cygwin.

• Operating system: Windows (tested on Windows 10 / Windows 11)
• PowerShell: Windows PowerShell 5.x or PowerShell 7+
• Permissions: Must be run from an elevated (Administrator) PowerShell session

1. Download or clone the repository

   git clone https://github.com/<your-username>/<your-repo-name>.git cd <your-repo-name>

2. Open PowerShell as Administrator

   • Start Menu → search for “PowerShell”
   • Right-click → “Run as administrator”

3. Run the script

   If your execution policy blocks the script, you can temporarily bypass it:

   Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass .\Uninstall-Cygwin.ps1

4. Reboot

   After the script completes, it is recommended to reboot Windows to ensure:

   • Any remaining cygwin1.dll instances are unloaded
   • Any open handles into previously deleted directories are released

The script is designed to be idempotent:

• If Cygwin has already been removed:
  • No services will match the Cygwin filter.
  • No Cygwin directories will be found.
  • PATH will already be cleaned.
  • Registry keys and shortcuts will not exist.

In that state, running the script again results in harmless “nothing to do” behaviour.

The script includes several safeguards:

• No deletion of drive roots

  Any path where Path == drive root (e.g. C:\) is explicitly skipped.

• Cygwin-only path deletion

  Directories are only eligible for deletion if their path contains the word cygwin (case-insensitive).

• Conservative cache deletion

  Package cache directories are only removed if:

  • They are discovered via Cygwin’s own registry entries, and
  • Their paths contain cygwin.

• Scoped environment cleaning

  Only PATH entries containing cygwin are removed. Other entries are preserved.

• It does not attempt to uninstall or modify:

  • WSL (Windows Subsystem for Linux)
  • MSYS / MSYS2
  • Git for Windows
  • Any non-Cygwin POSIX-like environment

• It does not remove:

  • Non-Cygwin directories that happen to contain other toolchains
  • Any files outside those explicitly matching Cygwin-related registry, path, or shortcut patterns

You need to start PowerShell with elevated rights:

1. Close the current PowerShell window.
2. Start Menu → type powershell.
3. Right-click → Run as administrator.
4. Run the script again.

The script attempts to take ownership and reset permissions using takeown.exe and icacls.exe.
If these still fail:

• Check if you have locked files in those directories (for example, a third-party antivirus or backup agent).
• Temporarily disable security tools that may be keeping handles open on the Cygwin directory.
• Reboot and re-run the script as Administrator.

Environment variable changes apply to future shells:

• Close and reopen PowerShell / Command Prompt.
• For GUI applications, log off and back on (or reboot) to ensure all processes see the updated PATH.

You can inspect current PATH variables with:

[Environment]::GetEnvironmentVariable('PATH', 'Machine') [Environment]::GetEnvironmentVariable('PATH', 'User')

You should not see any segments containing cygwin after the script has run.

You may wish to:

• Tighten or relax the matching rules for:
  • PATH entries (e.g. only match C:\cygwin64\bin)
  • Directory deletions (e.g. include additional known Cygwin install paths)
• Add logging to a file instead of console output
• Integrate with configuration management or automation tools

The script is structured into logical sections and helper functions to make such changes straightforward.

You are free to use, modify, and distribute this script.

A simple option is to license the repository under the MIT Licence.
For example:

MIT License Copyright (c) 2025 VibeCoder01 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: ...