git-patch-id(1) Git Manual git-patch-id(1)
NAME
git-patch-id - Compute unique IDs for patches
SYNOPSIS
git patch-id [--stable | --unstable | --verbatim]
DESCRIPTION
Read patches from standard input and compute the patch IDs.
A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated
with a patch, with line numbers ignored. As such, it's "reasonably
stable", but at the same time also reasonably unique, i.e., two patches
that have the same "patch ID" are almost guaranteed to be the same
thing.
The main usecase for this command is to look for likely duplicate
commits.
When 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.
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:
o 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.
o 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.
o 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.
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.
SEE ALSO
git-cherry(1)
GIT
Part of the git(1) suite
Git 2.54.0 2026-04-19 git-patch-id(1)
git 2.54.0 - Generated Fri Apr 24 08:52:26 CDT 2026