Vim replace DATE with date/time in Jekyll post template

.bashrc

# function to create a blog post, with date in name, and a timestamp
function blog() {
  BLOG_DIRECTORY="/home/philip/Projects/notes/_posts/"
  TEMPLATE=".template"
  cp ${BLOG_DIRECTORY}${TEMPLATE} $BLOG_DIRECTORY`date +%Y-%m-%d`-$1.md
  vi ${BLOG_DIRECTORY}"`date +%Y-%m-%d`"-$1.md -c ":%s/DATE/\=strftime(\"%y-%m-%d %H:%M:%S\")/g"
}

.template

---
layout: post
title: My title
date: DATE
categories: random
short_description: My description
---

Blog text here