$ git diff 8044225f2 --shortstatファイル単位なら、--stat。
$ git diff 8044225f2 --stat book/src/abc.c | 74 +++++++++++++++++++++++++++++++++++++++++---- book/src/page.c | 16 +++++++++--- book/test/foo.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----- 3 files changed, 198 insertions(+), 12 deletions(-)