Shorthand for diff of git commit with its parent?

Question

Aside from writing an alias or script, is there a shorter command for getting the diff for a particular commit?

git diff 15dc8^..15dc8

If you only give the single commit id git diff 15dc8, it diffs that commit against HEAD.

Answer 1

Use git show $COMMIT. It'll show you the log message for the commit, and the diff of that particular commit.

Answer 2

If you know how far back, you can try something like:

# Current branch vs. parent
git diff HEAD^ HEAD

# Current branch, diff between commits 2 and 3 times back
git diff HEAD~3 HEAD~2

Prior commits work something like this:

# Parent of HEAD
git show HEAD^1

# Grandparent
git show HEAD^2

There are a lot of ways you can specify commits:

# Great grandparent
git show HEAD~3

See this page for details.

Answer 3

Use git show COMMIT to get commit description and diff for a commit. If you want only diff, you can use git diff-tree -p COMMIT

And if you read git-rev-parse(1) manpage carefully, you would notice the following fragment:

Two other shorthands for naming a set that is formed by a commit and its parent commits exist. The r1^@ notation means all parents of r1. r1^! includes commit r1 but excludes all of its parents.

This means that you can use 15dc8^! as a shorthand for 15dc8^..15dc8 anywhere in git where revisions are needed.