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Diffstat (limited to 'Documentation/git-patch-id.txt')
| -rw-r--r-- | Documentation/git-patch-id.txt | 50 |
1 files changed, 36 insertions, 14 deletions
diff --git a/Documentation/git-patch-id.txt b/Documentation/git-patch-id.txt index 253fc0fc25..cf71fba1c0 100644 --- a/Documentation/git-patch-id.txt +++ b/Documentation/git-patch-id.txt @@ -7,18 +7,21 @@ git-patch-id - Compute unique ID for a patch SYNOPSIS -------- -'git patch-id' < <patch> +[verse] +'git patch-id' [--stable | --unstable] DESCRIPTION ----------- -A "patch ID" is nothing but a SHA1 of the diff 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. +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 +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. @@ -26,16 +29,35 @@ This can be used to make a mapping from patch ID to commit ID. OPTIONS ------- -<patch>:: - The diff to create the ID of. -Author ------- -Written by Linus Torvalds <torvalds@osdl.org> +--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. + + This is the default if patchid.stable is set to true. -Documentation --------------- -Documentation by Junio C Hamano and the git-list <git@vger.kernel.org>. +--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. + +<patch>:: + The diff to create the ID of. GIT --- |