GIT-PATCH-ID(1)

💖 NAME 💖

okay so welcome to the git-patch-id(1) page — yes bestie, it's the Git Manual entry for computing unique IDs for patches, and it's lowkey iconic. The command is git-patch-id, and it does exactly what the name says: it computes unique IDs for patches. periodt. 💅

✨ SYNOPSIS ✨

git patch-id [--stable | --unstable | --verbatim]

💅 DESCRIPTION 💅

So the vibe is: it reads patches from standard input and computes the patch IDs. That's the whole main-character job. 🎀

A “patch ID” is literally nothing but a sum of SHA-1 of the file diffs associated with a patch, with line numbers ignored. The way that works means it's “reasonably stable,” but also reasonably unique — like, two patches that have the same “patch ID” are almost guaranteed to be the same thing. no cap. 🦋

The main usecase for this command is to look for likely duplicate commits. That's the glow-up. ✨

When you're dealing with git diff-tree --patch output, it takes advantage of the fact that the patch is prefixed with the object name of the commit, and outputs two 40-byte hexadecimal strings. The first string is the patch ID, and the second string is the commit ID. This can be used to make a mapping from patch ID to commit ID for a set or range of commits. literally so useful. 💜

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🎀 OPTIONS 🎀

• --verbatim — Calculate the patch ID of the input as it is given, do not strip any whitespace. Implies --stable and forbids --unstable. This is the default if patchid.verbatim is true. 🫶
• --stable — Use a “stable” sum of hashes as the patch ID. With this option:
  • Reordering file diffs that make up a patch does not affect the ID. In particular, two patches produced by comparing the same two trees with two different settings for -O<orderfile> result in the same patch ID signature, thereby allowing the computed result to be used as a key to index some meta-information about the change between the two trees. 🧚
  • The result is different from the value produced by Git 1.9 and older or produced when an “unstable” hash (see --unstable below) is configured — even when used on a diff output taken without any use of -O<orderfile>, thereby making existing databases storing such “unstable” or historical patch IDs unusable. 😭
  • All whitespace within the patch is ignored and does not affect the ID. 🌸

This is the default if patchid.stable is set to true.

• --unstable — Use an “unstable” hash as the patch ID. With this option, the result produced is compatible with the patch ID value produced by Git 1.9 and older and whitespace is ignored. Users with pre-existing databases storing patch IDs produced by Git 1.9 and older (who do not deal with reordered patches) may want to use this option. This is the default. 🔥

bestie pls note: --verbatim implies --stable and forbids --unstable. don't mix and match unless you know what you're doing 💀

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🦋 EXAMPLES 🦋

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. slay. 👑

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🌈 SEE ALSO 🌈

git-cherry(1) — that's the one, bestie. go read it. 🍓

👑 GIT 👑

Part of the git(1) suite. obviously. 💖

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This page is from Git 2.56.0, dated 2026-09-27 — mwah, hope this helped, bye bestie 💋✨