dig: finding commit origins

The dig subcommand helps you trace a commit in your local git repository back to the original mailing list submission on a public-inbox instance such as lore.kernel.org.

This is useful when you need to find the discussion thread for an already-applied commit, identify the original recipients, or retrieve the full thread for reference.

Basic usage

Pass a commit-ish object to b4 dig:

$ b4 dig -c HEAD
$ b4 dig -c abc123
$ b4 dig -c v6.14-rc2~10

B4 will try several strategies to find the original submission, in order of reliability:

  1. Patch-id matching: computes a stable patch-id from the commit diff and searches for it on lore, trying multiple diff algorithms.

  2. Author email + subject: searches for the commit subject combined with the author’s email address.

  3. In-body From: line: when a patch was sent from a different email address than the commit author (common with contributors who have both personal and corporate addresses), git records the author identity in an in-body From: line. B4 searches for that exact string.

If the commit already contains Link: trailers pointing to public-inbox URLs, b4 will use those as well.

New in version v0.15.

Option flags

-c COMMITISH, --commitish COMMITISH

The commit to look up. Can be a SHA, tag, branch, or any valid git commit-ish expression.

-C, --no-cache

Bypass the local cache and fetch fresh results from the server.

-a, --all-series

Instead of showing only the best matching patch, show all revisions of the series that b4 can find. Useful for seeing the full history of a patch set.

-m DEST, --save-mbox DEST

Save the matched thread to the specified mbox file instead of just printing the link.

-w, --who

Show the list of people who were originally included in To and Cc of the matched patch. Useful for finding out who was involved in the original review.

Note

The -a, -m, and -w flags are mutually exclusive.

Examples

Find the mailing list link for a commit:

$ b4 dig -c e48e16f3e37f
---
[PATCH v3] f2fs: support non-4KB block size without packed_ssa feature
https://patch.msgid.link/20260110235405.2783424-1-daeho43@gmail.com

Show all revisions of the series containing a commit:

$ b4 dig -c e48e16f3e37f -a
---
This patch belongs in the following series:
---
  v1: [PATCH] f2fs: support non-4KB block size ...
  v2: [PATCH v2] f2fs: support non-4KB block size ...
  v3: [PATCH v3] f2fs: support non-4KB block size ...

Find who was on the original thread:

$ b4 dig -c abc123 -w
---
People originally included in this patch:
maintainer@example.org, reviewer@example.org, dev-list@example.org

Save the matched thread for offline review:

$ b4 dig -c abc123 -m /tmp/thread.mbx
Saved matched thread to /tmp/thread.mbx