使用git diff的一种方法是:

git diff <commit> <path>

引用上一次提交的一个提交的常用方法是作为实际HEAD的相对路径。你可以引用以前的提交HEAD^(在你的例子中这将是123abc)或HEAD^^(在你的例子中是456def)，等等…

所以你问题的答案是

git diff HEAD^^ myfile

这确实存在，但它实际上是git log的一个特性:

git log -p [-m] [--follow] [-1] <path>

注意-p也可以用来显示单次提交的内联差异:

git log -p -1 <commit>

选择使用:

-p (also -u or --patch) is hidden deeeeeeeep in the git-log man page, and is actually a display option for git-diff. When used with log, it shows the patch that would be generated for each commit, along with the commit information—and hides commits that do not touch the specified <path>. (This behavior is described in the paragraph on --full-diff, which causes the full diff of each commit to be shown.) -m causes merge commits to include the diff content (otherwise these just show the commit message, as if -p were not specified). -1 shows just the most recent change to the specified file (-n 1 can be used instead of -1); otherwise, all non-zero diffs of that file are shown. --follow is required to see changes that occurred prior to a rename.

据我所知，这是在不使用git log(或类似)来计算中间修订的数量或确定提交的哈希的情况下，立即查看对文件所做的最后一组更改的唯一方法。

若要查看较旧版本的更改，只需滚动日志，或指定开始日志的提交或标记。(当然，指定提交或标记会使您回到最初的问题，即确定正确的提交或标记是什么。)

应得的荣誉:

多亏了这个答案，我发现了log -p。 感谢FranciscoPuga和这个回答给我展示了-follow选项。 ChrisBetti提到了-n 1选项，atatko提到了-1变体。 感谢sweaver2112让我真正阅读文档并弄清楚-p在语义上“意味着”什么。 感谢Oscar Scholten指出，默认情况下，-p在合并提交时不显示diff-contents。

如果你擅长使用图形化工具，这将非常有效:

gitk <file>

Gitk现在显示文件已更新的所有提交。标记一次提交将显示列表中与前一次提交的差异。这也适用于目录，但随后您还需要为所选提交选择要进行差异的文件。超级有用啊!