从git diff（1）的手册页：

git diff [options] [<commit>] [--] [<path>…]
git diff [options] --cached [<commit>] [--] [<path>…]
git diff [options] <commit> <commit> [--] [<path>…]
git diff [options] <blob> <blob>
git diff [options] [--no-index] [--] <path> <path>

使用中间的第三个：

git diff [options] <parent-commit> <commit>

同样从同一手册页底部的示例部分：

$ git diff HEAD^ HEAD      <3>

比较上次提交和上次提交之前的版本。

诚然，它的措辞有点混乱，但也不会那么混乱

将最近的提交与之前的提交进行比较。

要查看特定COMMIT哈希的差异，其中COMMIT是提交的哈希：

gitdiffCOMMIT~COMMIT将向您展示COMMIT的祖先和COMMIT之间的区别。有关命令和gitrevisions的详细信息，请参阅gitdiff的手册页。

或者，gitshowCOMMIT也会做类似的事情。（提交的数据，包括其diff，但不包括合并提交的数据。）请参阅gitshow手册页。

（gitdiffCOMMIT也会显示COMMIT和头部之间的区别。）

另一种可能性：

git log -p COMMIT -1

还可以查看特定文件的两次提交之间的更改。

git diff <commit_Id_1> <commit_Id_2> some_dir/file.txt

检查文件更改的更简单方法（示例）

# 1. Checkout a branch and see the list of commits
git log --oneline -5

# > Output
9b9b1f8 (HEAD -> master) Updated ABC
d58e5da chore: Added files
5a4aa2c chore: Added my pipeline
bb2b0b7 feat: Added ABC
473f711 feat: Added ZYX

# 2. Pick a commit hash and check which files were modified
git show --stat --oneline d58e5da

# > Output
d58e5da chore: Added versioning files
 Someabcfile                            | 18 ++++++++++++++++++
 myfolder/file.py                       | 19 +++++++++++++++++++
 myfolder/file.js                       |  7 +++++++
 myfolder/file.txt                      |  1 +
 4 files changed, 45 insertions(+)

# 3. Pick a file to check the differences
git show d58e5da myfolder12/file.py

或者，从列表中检查一次提交中的所有文件差异：

git show d58e5da

一些答案漏掉了一个特例。如何查看根提交所做的更改，因为它没有父/祖先。

Both

git diff＜root_commit＞^<root_commit>

and

git diff＜root_commit＞~<root_commit>

抛出错误。

$git diff 27e521ca73a46b2d3a28568dc49fced81e46aaea~ 27e521ca73a46b2d3a28568dc49fced81e46aaea
fatal: ambiguous argument '27e521ca73a46b2d3a28568dc49fced81e46aaea~': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

git diff＜root_commit＞^！

显示diff btw根提交和HEAD。像这样：

$ git diff 27e521ca73a46b2d3a28568dc49fced81e46aaea^!
diff --git a/file1.txt b/file1.txt
new file mode 100644
index 0000000..80f3f1a
--- /dev/null
+++ b/file1.txt
@@ -0,0 +1,5 @@
+Create the first file.
+
+Add some placeholder text to first file.
+
+
diff --git a/file2.txt b/file2.txt
new file mode 100644
index 0000000..66e494f
--- /dev/null
+++ b/file2.txt
@@ -0,0 +1,6 @@
+This is the second file.
+
+It has an uncommited commit.
+
+We use it to demo default `git diff` behaviour.
+

（这些是所有提交对我的根提交和HEAD所做的更改）。

对于根提交

我只发现

git show--color--prett=格式：%b<root_commit_hash>

作品

像这样：

$ git show --color --pretty=format:%b 27e521ca73a46b2d3a28568dc49fced81e46aaea

diff --git a/README b/README
new file mode 100644
index 0000000..12a04f0
--- /dev/null
+++ b/README
@@ -0,0 +1,6 @@
+# git-diff-demo
+
+This repo documents the demo of the git diff command.
+We will have options, and use cases.

（我的根提交仅添加了README）