1GIT-PATCH-ID(1) Git Manual GIT-PATCH-ID(1)
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6 git-patch-id - Compute unique ID for a patch
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9 git patch-id [--stable | --unstable]
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12 Read a patch from the standard input and compute the patch ID for it.
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14 A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated
15 with a patch, with whitespace and line numbers ignored. As such, it’s
16 "reasonably stable", but at the same time also reasonably unique, i.e.,
17 two patches that have the same "patch ID" are almost guaranteed to be
18 the same thing.
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20 IOW, you can use this thing to look for likely duplicate commits.
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22 When dealing with git diff-tree output, it takes advantage of the fact
23 that the patch is prefixed with the object name of the commit, and
24 outputs two 40-byte hexadecimal strings. The first string is the patch
25 ID, and the second string is the commit ID. This can be used to make a
26 mapping from patch ID to commit ID.
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29 --stable
30 Use a "stable" sum of hashes as the patch ID. With this option:
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32 • Reordering file diffs that make up a patch does not affect the
33 ID. In particular, two patches produced by comparing the same
34 two trees with two different settings for "-O<orderfile>"
35 result in the same patch ID signature, thereby allowing the
36 computed result to be used as a key to index some
37 meta-information about the change between the two trees;
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39 • Result is different from the value produced by git 1.9 and
40 older or produced when an "unstable" hash (see --unstable
41 below) is configured - even when used on a diff output taken
42 without any use of "-O<orderfile>", thereby making existing
43 databases storing such "unstable" or historical patch-ids
44 unusable.
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46 This is the default if patchid.stable is set to true.
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48 --unstable
49 Use an "unstable" hash as the patch ID. With this option, the
50 result produced is compatible with the patch-id value produced by
51 git 1.9 and older. Users with pre-existing databases storing
52 patch-ids produced by git 1.9 and older (who do not deal with
53 reordered patches) may want to use this option.
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55 This is the default.
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58 Part of the git(1) suite
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62Git 2.36.1 2022-05-05 GIT-PATCH-ID(1)