git 查看文件先前版本差异的速记
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Shorthand to view diff of previous version of file
提问by Clayton
I can easily find out what changed for a file since the last commit with git diff HEAD^ -- <filename>but is there an equivalent shorthand to view a diff for a particular file since it was last committed, regardless of how many commits have happened since? Or to go back N commits of that particular file?
我可以很容易地找出自上次提交以来文件发生了什么变化，git diff HEAD^ -- <filename>但是否有等效的速记来查看自上次提交以来特定文件的差异，无论此后发生了多少次提交？或者返回该特定文件的 N 次提交？
Context:I found an error in a file and I want to track down when it snuck in. It's easy enough to get a log report for a particular file with git log -<n> <filename>to show only the commits that included changes to that file. So clearly I can just copy and paste the SHAs from that logreport, but what I really want is to be able to do something like git diff ^ -- <filename>or git diff ~2 -- <filename>.
上下文：我在一个文件中发现了一个错误，我想在它潜入时进行跟踪。获取特定文件的日志报告并git log -<n> <filename>仅显示包含对该文件的更改的提交很容易。很明显，我可以从该log报告中复制和粘贴 SHA ，但我真正想要的是能够执行诸如git diff ^ -- <filename>或 之类的操作git diff ~2 -- <filename>。
回答by Matt McHenry
$ git log -p <filename>
will show you the log message plus a diff for each commit that touched the named file.
将向您显示日志消息以及触及命名文件的每个提交的差异。
To show only differences to the previous version, ask for just one step in log history:
要仅显示与先前版本的差异，请在日志历史记录中仅要求一个步骤：
$ git log -1 -p <filename>
回答by Alex W
You can make use of git logformatting to get the hashes of previous commits to a file. For example,
您可以使用git log格式来获取以前提交到文件的哈希值。例如，
git log --pretty=format:'%h' -1 --skip=1 <filename>
will get you the 2nd to last commit to touch a specific file. In fact, if you don't specify a filename, this will get you the 2nd to last commit on the entire repository. To get older hashes, you might set up a git alias that calls a shell function, like this:
将使您成为倒数第二次接触特定文件的提交。事实上，如果您不指定文件名，这将使您在整个存储库中进行倒数第二次提交。要获得较旧的哈希值，您可以设置一个调用 shell 函数的 git 别名，如下所示：
[alias]
prior-hash = "!ph() { git log --pretty=format:'%h' -1 --skip= ; }; ph"
To use it, you'd type something like git prior-hash n <filename>, where n is the (n+1)th most recent version of the file. So 1 would be the 2nd to last commit to the file, 2 would be the 3rd to last, etc, and 0 would be the most recent commit to touch that file. And again, the filename is optional, if you want to examine the repo as a whole.
要使用它，您需要输入类似的内容git prior-hash n <filename>，其中 n 是文件的第 (n+1) 个最新版本。因此，1 将是对文件的倒数第二次提交，2 将是倒数第三次，依此类推，而 0 将是触摸该文件的最近一次提交。再说一次，如果您想从整体上检查存储库，文件名是可选的。
I'm sure you could figure out how to build a diff command from there:
我相信您可以弄清楚如何从那里构建 diff 命令：
[alias]
prior-hash = "!ph() { git log --pretty=format:'%h' -1 --skip= ; }; ph"
diff-prev-easy = "!dp() { git diff $(git prior-hash ).. ; }; dp"
which would be used similar to the prior-hash alias, git diff-prev-easy n <filename>. This would compare the (n+1)th last revision to the most recent revision of the file. If you wanted to instead compare the (n+1)th last revision to the nth last revision, it's a simple change:
这将类似于先验哈希别名git diff-prev-easy n <filename>. 这会将第 (n+1) 个最后修订版与文件的最新修订版进行比较。如果您想将第 (n+1) 个最后一个修订版与第 n 个最后一个修订版进行比较，这是一个简单的更改：
[alias]
prior-hash = "!ph() { git log --pretty=format:'%h' -1 --skip= ; }; ph"
diff-prev = "!dp() { git diff $(git prior-hash )..$(git prior-hash $(( - 1)) ) ; }; dp"
which, again, is used the same way: git diff-prev n <filename>
再次以相同的方式使用： git diff-prev n <filename>
One potential problem to watch out for, though, is that git loglists commits in chronological order, which may not be what you want. Consider this history:
但是，需要注意的一个潜在问题是git log按时间顺序列出提交，这可能不是您想要的。想想这段历史：
1 - 2 - - - 4 - 5 master
\ /
3 - - develop
Our git diff-prev 1command would produce the diff between commit 4 and 5, as expected. But git diff-prev 2would show the diff between commit 3 and 4, which is likely undesirable.
git diff-prev 1正如预期的那样，我们的命令将在提交 4 和 5 之间产生差异。但是git diff-prev 2会显示提交 3 和 4 之间的差异，这可能是不可取的。
回答by Mike Monkiewicz
git blameshould get you to your destination pretty fast.
git blame应该可以让你很快到达目的地。
