Single repository::

  git log --pretty=format:%cs | cut -b 1-7|sort | uniq -c | add-missing-months  | awk '{print $1}' | spark

Multiple repositories::

  for d in */; do cd $d; basename $(pwd); git log --pretty=format:%cs | cut -b 1-7|sort | uniq -c | add-missing-months  | awk '{print $1}' | spark; cd ../; done


Links
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- spark: https://github.com/holman/spark