git diff中的“index f2e4113..d4b9bfc 100644”如何对应gitk中的SHA1 ID？

Question

'index f2e4113..d4b9bfc 100644'在git diff的输出中意味着什么？直到现在我已经假设这些SHA1 ID是from_version..to_version，但我无法在gitk中找到它们。

$ git --version 
git version 1.8.3.4 
$ git diff ae1fdc1 
diff --git a/README b/README 
index f2e4113..d4b9bfc 100644 
--- a/README 
+++ b/README 
@@ -1 +1,3 @@ 
stuff 
+more 
+more stuff 

'index f2e4113..d4b9bfc 100644'看起来不像差异统一格式的一部分。 http://en.wikipedia.org/wiki/Diff#Unified_format

100644看起来像文件模式，但不对应于自述文件（660）的模式。

f2e4113..d4b9bfc是SHA1 ID shorties。 'git rev-parse'给出了长SHA1。下面是来自例如所有三个矮仔上面：

ae1fdc1 - ae1fdc1e7b2f018a15c421f2f22b7c77215c5d61 
d4b9bfc - d4b9bfcd51a3eaf427d337a30b12d1f3dbdd21b4 
f2e4113 - f2e41136eac73c39554dede1fd7e67b12502d577 

但为什么不ae1fdc1对应于DIFF的第一或第二部分？ 为什么我找不到使用gitk的d4b9bfc或d4b9bfc？

Answer 1

编辑：@wiswit指出this很好的解释。

f2e4113和d4b9bfc是文件索引。使用git show f2e4113您可以在提交之前看到该文件，并在提交之后显示文件git show d4b9bfc。

组合diff格式是在git diff手册页中描述的。

COMBINED DIFF FORMAT 
    Any diff-generating command can take the ‘-c` or --cc option to produce a 
    combined diff when showing a merge. This is the default format when showing 
    merges with git-diff(1) or git-show(1). Note also that you can give the `-m’ 
    option to any of these commands to force generation of diffs with individual 
    parents of a merge. 

    A combined diff format looks like this: 

     diff --combined describe.c 
     index fabadb8,cc95eb0..4866510 
     --- a/describe.c 
     +++ b/describe.c 
     @@@ -98,20 -98,12 +98,20 @@@ 
       return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1; 
     } 

     - static void describe(char *arg) 
     -static void describe(struct commit *cmit, int last_one) 
     ++static void describe(char *arg, int last_one) 
     { 
     +  unsigned char sha1[20]; 
     +  struct commit *cmit; 
       struct commit_list *list; 
       static int initialized = 0; 
       struct commit_name *n; 

     +  if (get_sha1(arg, sha1) < 0) 
     +    usage(describe_usage); 
     +  cmit = lookup_commit_reference(sha1); 
     +  if (!cmit) 
     +    usage(describe_usage); 
     + 
       if (!initialized) { 
         initialized = 1; 
         for_each_ref(get_name); 

    1. It is preceded with a "git diff" header, that looks like this (when -c 
     option is used): 

      diff --combined file 

     or like this (when --cc option is used): 

      diff --cc file 

    2. It is followed by one or more extended header lines (this example shows 
     a merge with two parents): 

      index <hash>,<hash>..<hash> 
      mode <mode>,<mode>..<mode> 
      new file mode <mode> 
      deleted file mode <mode>,<mode> 

     The mode <mode>,<mode>..<mode> line appears only if at least one of the 
     <mode> is different from the rest. Extended headers with information 
     about detected contents movement (renames and copying detection) are 
     designed to work with diff of two <tree-ish> and are not used by combined 
     diff format. 

    3. It is followed by two-line from-file/to-file header 

      --- a/file 
      +++ b/file 

     Similar to two-line header for traditional unified diff format, 
     /dev/null is used to signal created or deleted files. 

    4. Chunk header format is modified to prevent people from accidentally 
     feeding it to patch -p1. Combined diff format was created for review 
     of merge commit changes, and was not meant for apply. The change is 
     similar to the change in the extended index header: 

      @@@ <from-file-range> <from-file-range> <to-file-range> @@@ 

     There are (number of parents + 1) @ characters in the chunk header for 
     combined diff format. 

    Unlike the traditional unified diff format, which shows two files A and B 
    with a single column that has - (minus — appears in A but removed in B), 
    + (plus — missing in A but added to B), or " " (space — unchanged) prefix, 
    this format compares two or more files file1, file2,... with one file X, 
    and shows how X differs from each of fileN. One column for each of fileN is 
    prepended to the output line to note how X’s line is different from it. 

    A - character in the column N means that the line appears in fileN but it 
    does not appear in the result. A + character in the column N means that 
    the line appears in the result, and fileN does not have that line (in 
    other words, the line was added, from the point of view of that parent). 

    In the above example output, the function signature was changed from both 
    files (hence two - removals from both file1 and file2, plus ++ to mean one 
    line that was added does not appear in either file1 nor file2). Also eight 
    other lines are the same from file1 but do not appear in file2 (hence 
    prefixed with +). 

    When shown by git diff-tree -c, it compares the parents of a merge commit 
    with the merge result (i.e. file1..fileN are the parents). When shown by 
    git diff-files -c, it compares the two unresolved merge parents with the 
    working tree file (i.e. file1 is stage 2 aka "our version", file2 is stage 
    3 aka "their version").