Shorthand for getting the diff from the last N commits?

Question

I know I can do:

git diff HEAD^..HEAD 

But is there some shorthand that's easier to remember, like:

git diff foo N 

where N can be any number of commits from now to get a cumulative diff of?

Answer 1

From the SPECIFYING REVISIONS of the git rev-parse man page:

A suffix ~<n> to a revision parameter means the commit object that is the <n>th generation grand-parent of the named commit object, following only the first parent.
I.e. rev~3 is equivalent to rev^^^ which is equivalent to rev^1^1^1.

Consider the examples in the git diff man page:

git diff HEAD^..HEAD git diff HEAD^.. git diff HEAD^ HEAD 

are equivalent forms (thanks chrisk for the HEAD^.. form, as mentioned in the comments).
(they are not equivalent to git diff HEAD^, as Mark Longair comments, since it diff with the working directory, not the last commit)

So:

git diff HEAD~15       # diff the working tree with the 15th previous commit git diff HEAD~15 HEAD  # diff the last commit  with the 15th previous commit 

should do what you need (as khmarbaise mentions in the comment).

Answer 2

Use git diff HEAD~N. Or use git diff HEAD~N.. to exclude uncommitted changes.