Install pacman on Windows Git Bash

This script bootstraps an MSYS2-like environment inside Windows Git Bash.
It downloads essential MSYS2 packages, extracts them, copies them to a Git Bash root directory structure, initializes the pacman keyring, and performs a full system upgrade inside this environment.

It is intended for Git Bash users on Windows who want to use pacman and related tools without installing a full MSYS2 distribution.

• Downloads pacman, pacman-mirrors, and msys2-keyring packages.
• Supports choosing between:
  • Official MSYS2 mirror (https://mirror.msys2.org)
  • Tsinghua University mirror (recommended for users in mainland China)
• Automatically extracts .pkg.tar.zst files using 7-Zip 24.01+.
• Copies files to a Git Bash root directory, overwriting if necessary.
• Initializes and populates the pacman keyring in Git Bash.
• Performs a system upgrade with pacman -Syu inside Git Bash.
• Optional cleanup of temporary download and extraction directories.
• Fully colored output for better visibility.
• Supports non-interactive automation for CI or scripting.

• Windows OS (script must run in Git Bash).
  The script will fail if run on Linux, macOS, or WSL.
• Git Bash installed and run as Administrator.
• 7-Zip version 24.01 or newer installed and accessible in PATH or at:

  C:\Program Files\7-Zip\7z.exe 

• Internet access to download MSYS2 packages from your chosen mirror.

Run the script normally to select mirror and cleanup options interactively:

bash <(curl -fsSL https://raw.githubusercontent.com/dameng324/install-pacman-on-git-bash/main/install.sh)

For automation (CI/CD or unattended setups), use the following options:

bash <(curl -fsSL https://raw.githubusercontent.com/dameng324/install-pacman-on-git-bash/main/install.sh) --non-interactive --mirror tsinghua --cleanup

• Administrator privileges are required because files are copied to the Git Bash root directory structure.
• The script outputs clear, colored steps and warnings for easy monitoring.
• If you experience download failures, verify your internet connection and mirror accessibility.
• Temporary directories (downloads and extraction) are kept by default unless cleanup is chosen.
• This script is not intended for full MSYS2 users; if you already have MSYS2, pacman is already included.

This script is provided as-is under the MIT License. Use at your own risk.