From 1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Sat, 11 Jan 2020 23:36:56 +0000 Subject: Squashed 'third_party/git/' content from commit cb71568594 git-subtree-dir: third_party/git git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7 --- Documentation/git-patch-id.txt | 61 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 Documentation/git-patch-id.txt (limited to 'Documentation/git-patch-id.txt') diff --git a/Documentation/git-patch-id.txt b/Documentation/git-patch-id.txt new file mode 100644 index 000000000000..442caff8a9c3 --- /dev/null +++ b/Documentation/git-patch-id.txt @@ -0,0 +1,61 @@ +git-patch-id(1) +=============== + +NAME +---- +git-patch-id - Compute unique ID for a patch + +SYNOPSIS +-------- +[verse] +'git patch-id' [--stable | --unstable] + +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 whitespace and 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. + +IOW, you can use this thing 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 +------- + +--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" 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", thereby making existing databases storing such + "unstable" or historical patch-ids unusable. + + 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. 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 linkgit:git[1] suite -- cgit 1.4.1