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Diffstat (limited to 'Documentation/git-patch-id.txt')
| -rw-r--r-- | Documentation/git-patch-id.txt | 39 |
1 files changed, 34 insertions, 5 deletions
diff --git a/Documentation/git-patch-id.txt b/Documentation/git-patch-id.txt index 90268f02e7..cf71fba1c0 100644 --- a/Documentation/git-patch-id.txt +++ b/Documentation/git-patch-id.txt @@ -8,14 +8,16 @@ git-patch-id - Compute unique ID for a patch SYNOPSIS -------- [verse] -'git patch-id' < <patch> +'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. @@ -27,6 +29,33 @@ 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<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. + +--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. |