git diff在分支的x提交中更改了文件

Question

The task is to output files that have been changed in last 5 commits of the origin/1.5.0 branch.

Without the branch requirement I came up with: git diff --name-only HEAD~5 . With the branch requirement I tried git diff --name-only HEAD~5 --first-parent origin/1.5.0 but the output is longer. Adding condition shouldn't produce more results which means there's something I don't understand. Where have I gone wrong?

Answer 1

The git diff command always ¹ compares two commits-or-file-trees. The options and arguments select which two (and how to do the diff, eg, --name-only or --name-status skips the patch part of the diff).

If you run git diff HEAD~5 , the two things you selected are:

1. HEAD~5 : the commit five steps back from HEAD , the current commit
2. the current work-tree

For comparison, if you run git diff --cached HEAD~5 , you select instead HEAD~5 and the current index , and if you run git diff HEAD~10 HEAD~5 you select instead HEAD~10 and HEAD~5 .

Note that the ~ number syntax comes from gitrevisions . A tilde suffix followed by an integer may be applied to any other commit selector, such as a raw hash ID, the name HEAD , the name of one of your own branches or tags, or the name of any of your remote-tracking branches . Since origin/1.5.0 is the name of a remote-tracking branch, you can use that to specify the commit to which that name points, or add a tilde and a number to move that many first-parent steps back from that point.

Hence:

git diff --name-only origin/1.5.0~5 origin/1.5.0

will compare the two specified commits, showing only the names of files that are not the same in those two commits.

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¹ You can make it behave differently in some interesting cases, but they are not the ones we care about here.

Answer 2

I think with "origin/1.5.0", the command changed to compare HEAD~5 with the branch origin/1.5.0. That is a much different diff than without branch.