1GIT-PATCH-ID(1)                   Git Manual                   GIT-PATCH-ID(1)
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NAME

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

9       git patch-id [--stable | --unstable]
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DESCRIPTION

13       Read a patch from the standard input and compute the patch ID for it.
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15       A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated
16       with a patch, with whitespace and line numbers ignored. As such, it’s
17       "reasonably stable", but at the same time also reasonably unique, i.e.,
18       two patches that have the same "patch ID" are almost guaranteed to be
19       the same thing.
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21       IOW, you can use this thing to look for likely duplicate commits.
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23       When dealing with git diff-tree output, it takes advantage of the fact
24       that the patch is prefixed with the object name of the commit, and
25       outputs two 40-byte hexadecimal strings. The first string is the patch
26       ID, and the second string is the commit ID. This can be used to make a
27       mapping from patch ID to commit ID.
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OPTIONS

30       --stable
31           Use a "stable" sum of hashes as the patch ID. With this option:
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33           ·   Reordering file diffs that make up a patch does not affect the
34               ID. In particular, two patches produced by comparing the same
35               two trees with two different settings for "-O<orderfile>"
36               result in the same patch ID signature, thereby allowing the
37               computed result to be used as a key to index some
38               meta-information about the change between the two trees;
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40           ·   Result is different from the value produced by git 1.9 and
41               older or produced when an "unstable" hash (see --unstable
42               below) is configured - even when used on a diff output taken
43               without any use of "-O<orderfile>", thereby making existing
44               databases storing such "unstable" or historical patch-ids
45               unusable.
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47                   This is the default if patchid.stable is set to true.
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49       --unstable
50           Use an "unstable" hash as the patch ID. With this option, the
51           result produced is compatible with the patch-id value produced by
52           git 1.9 and older. Users with pre-existing databases storing
53           patch-ids produced by git 1.9 and older (who do not deal with
54           reordered patches) may want to use this option.
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56               This is the default.
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GIT

59       Part of the git(1) suite
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63Git 2.20.1                        12/15/2018                   GIT-PATCH-ID(1)
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