PR Mirror

prmirror.sh is a shell script to mirror an existing pull request from a public GitHub repository by:

1. Cloning the repo (via SSH),
2. Fetching the pull request as a local branch,
3. Creating a new branch based on it with an empty signed commit (to distinguish the mirror),
4. Pushing the branch to the same repo,
5. Opening a new pull request (via the GitHub CLI) from the mirrored branch into a specified base branch.

This is useful in scenarios like:

• Creating a filtered or internal mirror of external PRs
• Testing PRs against a different base branch (e.g., staging instead of main)

Prerequisites

git (must be in PATH)

GitHub CLI (gh) installed and authenticated (via gh auth login)

SSH access to GitHub (git@github.com must be reachable)

Usage

./prmirror.sh -n <pr-number> -b <base-branch> -o <org> -r <repo> [-s]

Arguments

Flag	Description
-n	(Required) Pull request number to mirror
-b	(Required) Base branch to target for the new PR
-o	(Required) GitHub organization (e.g. PandasWhoCode)
-r	(Required) GitHub repository name (e.g. pr-mirror)
-s	(Optional) Sync the mirror-pr branch and update the mirror PR

Example (Create new mirror)

./prmirror.sh -n 42 -b main -o PandasWhoCode -r pr-mirror

This will:

• Clone git@github.com:PandasWhoCode/pr-mirror.git into a temporary mirror-repo directory
• Fetch pull request #42 into a temporary branch
• Create a new branch mirror/pr-42 from it
• Add an empty signed commit for traceability
• Push mirror/pr-42 to origin
• Open a new pull request targeting main, authored by your GitHub CLI user

Output

The new PR will be titled:

chore:Mirror PR-42

And will include all commits from the original PR, along with an empty commit to mark it as mirrored.

Example (Sync existing mirror)

./prmirror.sh -n 42 -b main -o PandasWhoCode -r pr-mirror -s

This will:

• Clone git@github.com:PandasWhoCode/pr-mirror.git into a temporary mirror-repo directory
• Fetch pull request #42 into a temporary branch
• Sync the branch mirror/pr-42 from with the temporary branch
• Add an empty signed commit for traceability
• Push mirror/pr-42 to origin

Output

The existing mirror PR will be titled:

chore: Mirror PR-42 (sync)

The PR will include all commits from the original PR, along with an empty commit to mark it as mirrored.

Notes

The script exports GITHUB_TOKEN and GITHUB_UNAME using the GitHub CLI so that gh pr create can assign the author correctly.

The mirror-repo directory is created in the current working directory and not deleted automatically — you can remove it manually after use.

License

Apache 2.0