git-diff-index

Compare index to commit

$ git diff-index HEAD

$ git diff-index [commit]

$ git diff-index --quiet HEAD

$ git diff-index --raw HEAD

git diff-index [options] tree-ish [files...]

git diff-index compares a tree object to the working tree or index, operating as a low-level plumbing command used internally by git diff for commit comparisons. It accepts a tree-ish (commit, branch, tag, or tree object) and compares it against either the index (with --cached) or the working tree.
The tool is particularly useful in automation scenarios that need to detect whether files have changed since a specific commit, such as CI/CD pipelines checking for uncommitted modifications or scripts validating clean working directories. Its --quiet flag enables simple boolean checks for changes without processing full diff output.

--cached

Compare tree to index only.

Raw diff output.

Exit with 1 if differences.

Show file names only.

Show file names and status.

git-diff(1), git-diff-tree(1)