Find and replace

It can be convenient to find and replace by a given list of files from the command line:

replace foo bar **/*.rb

My replace script looks like this:

#!/bin/bash

find_this="$1"
shift
replace_with="$1"
shift

items=$(ag -l --nocolor "$find_this" "$@")
IFS=$'\n'
for item in $items; do
  sed "s/$find_this/$replace_with/g" "$item" > tmpfile && mv tmpfile "$item"
done