git-replace.sh

#!/bin/bash

if ! type sd &>/dev/null; then
  echo "sd: command not found" >&2
  exit 1
fi

case "${#}" in
  0)
    echo "too few arguments" >&2
    exit 1
    ;;
  1)
    # same as git grep
    git grep "${1}"
    ;;
  2)
    git grep -l "${1}" | xargs -I% sd "${1}" "${2}" %
    ;;
  *)
    input="${1}"
    output="${2}"
    shift 2
    git grep -l "${input}" "${@}" | xargs -I% sd "${input}" "${output}" %
    ;;
esac