NAME

       git-patch-id - Compute unique ID for a patch

SYNOPSIS

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

DESCRIPTION

       Read a patch from the standard input and compute the patch ID for it.

       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 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.

OPTIONS

       --verbatim
           Calculate the patch-id of the input as it is given, do not strip any whitespace.

               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;

           •   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.

GIT

       Part of the git(1) suite