Which option in Git Blame is used to filter only the commit hash? code example

Example: Git blame get users most edited file

#!/bin/bash

# save as i.e.: git-authors and set the executable flag
git ls-tree -r -z --name-only HEAD -- $1 | xargs -0 -n1 git blame \
 --line-porcelain HEAD |grep  "^author "|sort|uniq -c|sort -nr