projects / thirdparty / git.git / blame
| Commit | Line | Data |
|---|---|---|
| 7fc9d69f JH |
1 | git-patch-id(1) |
| 2 | =============== | |
| 3 | ||
| 4 | NAME | |
| 5 | ---- | |
| c3f0baac | 6 | git-patch-id - Compute unique ID for a patch |
| 7fc9d69f JH |
7 | |
| 8 | SYNOPSIS | |
| 9 | -------- | |
| 7791a1d9 | 10 | [verse] |
| 33e8fc87 | 11 | 'git patch-id' [--stable | --unstable] |
| 7fc9d69f JH |
12 | |
| 13 | DESCRIPTION | |
| 14 | ----------- | |
| 33e8fc87 JH |
15 | Read a patch from the standard input and compute the patch ID for it. |
| 16 | ||
| 30e12b92 MT |
17 | A "patch ID" is nothing but a sum of SHA-1 of the file diffs associated with a |
| 18 | patch, with whitespace and line numbers ignored. As such, it's "reasonably | |
| 19 | stable", but at the same time also reasonably unique, i.e., two patches that | |
| 20 | have the same "patch ID" are almost guaranteed to be the same thing. | |
| 7fc9d69f | 21 | |
| 52a22d1e | 22 | IOW, you can use this thing to look for likely duplicate commits. |
| 7fc9d69f | 23 | |
| 0b444cdb | 24 | When dealing with 'git diff-tree' output, it takes advantage of |
| a77a9222 | 25 | the fact that the patch is prefixed with the object name of the |
| 4fa535a1 | 26 | commit, and outputs two 40-byte hexadecimal strings. The first |
| a77a9222 JH |
27 | string is the patch ID, and the second string is the commit ID. |
| 28 | This can be used to make a mapping from patch ID to commit ID. | |
| 29 | ||
| 7fc9d69f JH |
30 | OPTIONS |
| 31 | ------- | |
| 30e12b92 MT |
32 | |
| 33 | --stable:: | |
| 34 | Use a "stable" sum of hashes as the patch ID. With this option: | |
| 35 | - Reordering file diffs that make up a patch does not affect the ID. | |
| 36 | In particular, two patches produced by comparing the same two trees | |
| 37 | with two different settings for "-O<orderfile>" result in the same | |
| 38 | patch ID signature, thereby allowing the computed result to be used | |
| 39 | as a key to index some meta-information about the change between | |
| 40 | the two trees; | |
| 41 | ||
| 42 | - Result is different from the value produced by git 1.9 and older | |
| 43 | or produced when an "unstable" hash (see --unstable below) is | |
| 44 | configured - even when used on a diff output taken without any use | |
| 45 | of "-O<orderfile>", thereby making existing databases storing such | |
| 46 | "unstable" or historical patch-ids unusable. | |
| 47 | ||
| 48 | This is the default if patchid.stable is set to true. | |
| 49 | ||
| 50 | --unstable:: | |
| 51 | Use an "unstable" hash as the patch ID. With this option, | |
| 52 | the result produced is compatible with the patch-id value produced | |
| 53 | by git 1.9 and older. Users with pre-existing databases storing | |
| 54 | patch-ids produced by git 1.9 and older (who do not deal with reordered | |
| 55 | patches) may want to use this option. | |
| 56 | ||
| 57 | This is the default. | |
| 58 | ||
| 7fc9d69f JH |
59 | GIT |
| 60 | --- | |
| 9e1f0a85 | 61 | Part of the linkgit:git[1] suite |