List merged branches

Before you begin

• Python 3.12 or later.
• Git must be installed on PATH. --repo must be an existing non-bare repository.

Set up your example

1. Save as git-merged-branch-report.py.
2. Open a terminal in its folder.
3. Run python "git-merged-branch-report.py" --help and prepare the listed input files.

This recipe uses your own local input or creates its own example output. Follow the setup steps below.

Download the ZIP, extract it, and open a terminal inside the extracted folder. The source file is git-merged-branch-report.py.

Run the script

python "git-merged-branch-report.py" --reference HEAD

If your system uses python3 instead of python, use that command for Python examples. Keep paths containing spaces in quotes. Required inputs and optional settings are described in the code and setup steps.

What to expect

The complete script

#!/usr/bin/env python3
"""Report local branches whose tips are reachable from a selected local reference."""
import argparse
import sys
import json
from pathlib import Path
import os
import subprocess
from collections import Counter
from datetime import datetime, timezone

def git(repo,*arguments,allow=(0,)):
    env=dict(os.environ,GIT_OPTIONAL_LOCKS='0',GIT_PAGER='cat',GIT_TERMINAL_PROMPT='0')
    result=subprocess.run(['git','--no-pager','--no-optional-locks','-C',str(repo),*arguments],capture_output=True,timeout=60,env=env)
    if result.returncode not in allow:
        raise RuntimeError(result.stderr.decode('utf-8','replace').strip() or f'git exited {result.returncode}')
    return result.stdout

def text(repo,*arguments,allow=(0,)):
    return git(repo,*arguments,allow=allow).decode('utf-8','replace')

def main():
    parser = argparse.ArgumentParser(description='Report local branches whose tips are reachable from a selected local reference.')
    parser.add_argument("--repo",type=Path,default=Path("."))
    parser.add_argument('--reference',default='HEAD')
    args = parser.parse_args()
    repo=Path(text(args.repo,"rev-parse","--show-toplevel").strip())
    
    commit=text(repo,'rev-parse','--verify',args.reference+'^{commit}').strip()
    print(text(repo,'branch','--merged',commit,'--format=%(refname:short)'),end='')

if __name__ == '__main__':
    try:
        main()
    except (OSError, ValueError, RuntimeError) as exc:
        print(f'Error: {exc}', file=sys.stderr)
        sys.exit(1)

Open source as plain text · Download source and sample files

How it works

1. Report local branches whose tips are reachable from a selected local reference.
2. Arguments are explicit and expected input errors produce a message with a nonzero exit code.
3. Results reflect your selected local data or the specific endpoint you choose; the example illustrates the result shape.

Make it your own

Adapt the task

Set --reference to a known local main or release branch.

Adjust presentation

Edit final print statements or json.dumps indentation to adjust the report layout. Keep input validation and exclusive-create file modes intact.

Change one setting at a time, run it again on sample data, and compare the output. The customization guide walks through this process.

If something goes wrong

Reference & next steps

• Git git-branch documentation ↗

These official references explain the underlying tools. The Scriptage example and guide are original instructional content. See verification notes for what has been checked and the limits of those checks.

Copies a template for your own notes. It does not send anything.