blob_src.sh

#!/usr/bin/env bash

name="$1"
if [ -z "$name" ]; then
  echo >&2 "usage: "$0" <filename>"
  exit 1
fi

what="$(git ls-files -s | grep "\t$name$" | awk '{ print $2 }')"

while read l; do
  sha="$(echo "$l" | awk '{ print $1 }')"
  tree="$(git ls-tree "$sha" -r)"
  dtree="$(git diff-tree -r --no-commit-id "$sha")"

  found="$(echo "$tree" | grep -c "$what")"
  dfound="$(echo "$dtree" | awk '{ print $4 }' | grep "$what")"

  if [ "0" -ne "$found" ]; then
    echo "  found $what in $sha";
  fi

  if [ ! -z "$dfound" ]; then
    echo "$what introduced in $sha";
    exit 0
  fi
done < <(git log --oneline)