From: kristofferhaugsbakk@fastmail.com Date: Sat, 14 Feb 2026 11:55:42 GMT Subject: [PATCH v2 2/3] doc: patch-id: add script example Message-ID: In-Reply-To: From: Kristoffer Haugsbakk The utility and usability of git-patch-id(1) was discussed relatively recently:[1] Using "git patch-id" is definitely in the "write a script for it" category. I don't think I've ever used it as-is from the command line as part of a one-liner. It's very much a command that is designed purely for scripting, the interface is just odd and baroque and doesn't really make sense for one-liners. The typical use of patch-id is to generate two *lists* of patch-ids, then sort them and use the patch-id as a key to find commits that look the same. The command doc *could* use an example, and since it is a mapper command it makes sense for that example to be a little script. Mapping the commits of some branch to an upstream ref allows us to demonstrate generating two lists, sorting them, joining them, and finally discarding the patch ID lookup column with cut(1). † 1: https://lore.kernel.org/workflows/CAHk-=wiN+8EUoik4UeAJ-HPSU7hczQP+8+_uP3vtAy_=YfJ9PQ@mail.gmail.com/ Inspired-by: Linus Torvalds Signed-off-by: Kristoffer Haugsbakk --- Notes (series): v2: • Delete temporary files • Use my weird daggers consistently for footnotes v1: The script will not list the commits in rev-list order because of the sorting. Documentation/git-patch-id.adoc | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/Documentation/git-patch-id.adoc b/Documentation/git-patch-id.adoc index e95391cd255..1618994e76c 100644 --- a/Documentation/git-patch-id.adoc +++ b/Documentation/git-patch-id.adoc @@ -68,6 +68,46 @@ This is the default if `patchid.stable` is set to `true`. + This is the default. +EXAMPLES +-------- + +linkgit:git-cherry[1] shows what commits from a branch have patch ID +equivalent commits in some upstream branch. But it only tells you +whether such a commit exists or not. What if you wanted to know the +relevant commits in the upstream? We can use this command to make a +mapping between your branch and the upstream branch: + +---- +#!/bin/sh + +upstream="$1" +branch="$2" +test -z "$branch" && branch=HEAD +limit="$3" +if test -n "$limit" +then + tail_opts="$limit".."$upstream" +else + since=$(git log --format=%aI "$upstream".."$branch" | tail -1) + tail_opts=--since="$since"' '"$upstream" +fi +for_branch=$(mktemp) +for_upstream=$(mktemp) + +git rev-list --no-merges "$upstream".."$branch" | + git diff-tree --patch --stdin | + git patch-id --stable | sort >"$for_branch" +git rev-list --no-merges $tail_opts | + git diff-tree --patch --stdin | + git patch-id --stable | sort >"$for_upstream" +join -a1 "$for_branch" "$for_upstream" | cut -d' ' -f2,3 +rm "$for_branch" +rm "$for_upstream" +---- + +Now the first column shows the commit from your branch and the second +column shows the patch ID equivalent commit, if it exists. + GIT --- Part of the linkgit:git[1] suite -- 2.53.0.26.g2afa8602a26