为何在master分支执行git diff-tree命令无返回结果？

Let’s break down exactly what’s happening here:

1. Master branch’s HEAD is a root commit (no parent) #

The core behavior of git diff-tree when you only pass one tree-ish (like HEAD) is that it compares that commit to its immediate parent commit. If your master branch’s HEAD is the very first commit in the repository (a root commit), it has no parent to compare against. That’s why git diff-tree returns nothing—there’s no prior commit state to calculate a difference from.

In the other branch you tested, the HEAD commit has at least one parent, so Git can compute the diff between the commit and its parent, hence showing the modified files.

2. Verify if it’s a root commit #

To confirm this theory, run this command on your master branch:

git rev-parse HEAD^

If you get an error like fatal: ambiguous argument 'HEAD^': unknown revision or path not in the working tree., that’s definitive proof your HEAD is a root commit with no parent.

3. Why your second command also fails #

When you ran:

git diff-tree --name-only -r HEAD HEAD^ path/to/modified-file

This tries to directly compare HEAD to HEAD^, but since HEAD^ doesn’t exist (no parent commit), Git can’t perform the diff—so you get no output here either.

How to see files in the root commit #

If you want to list the files included in that initial master commit, use git show instead. It handles root commits by displaying the full commit content rather than requiring a parent comparison:

git show --name-only HEAD

内容的提问来源于stack exchange，提问作者Oleg Pavliv