#!/usr/bin/env miaou-bash

function usage {
  builtin echo "Usage: $(basename "$0") <FILE> <REGEX> <STRING>"
}

[[ $# -ne 3 ]] && usage && exit 2

FILE=$1
REGEX=$2
STRING=$3

if ! grep -Pq "$REGEX" "$FILE"; then
  builtin echo -e "$STRING" >>"$FILE"
  echo 'appended'
else
  sed -Ei "s|$REGEX|$STRING|g" "$FILE"
  echo 'replaced'
fi
