Git pre-commit hook, taking a screenshot of a single webpage

pre-commit

#!/usr/bin/env bash

HOMEPAGE=http://localhost:5000
SCREENIE_DIR=$(pwd)/screenshots
HEAD=$(git rev-parse HEAD)

if [[ "$OSTYPE" == "darwin"* ]]; then
    RESPONSE=$(curl --write-out %{http_code} --silent --output /dev/null "$HOMEPAGE")
    if [[ "$RESPONSE" == 200 ]]; then
        mkdir -p "$SCREENIE_DIR"
        OUTPUT="$(date +'%s')-$HEAD.png"
        webkit2png --dir "$SCREENIE_DIR" -o "$OUTPUT" "$HOMEPAGE"
        git add "$SCREENIE_DIR"
        exit 0
    else
        echo "Stopping. Please start the server manually,"
        echo "so we can take our photograph. Or run 'git commit --no-verify'"
        echo "$HOMEPAGE response was $RESPONSE"
        exit 1
    fi
fi