Basic uptime monitor

uptime.sh

#!/bin/bash

NOTIFY_FROM="no-reply@example.com"
NOTIFY_TO="hi@example.com"

URLS=(
    "https://example.com"
    "https://google.com"
)

function is_up {
    curl -s --head --request GET "$1" | grep "200 OK"
}

REPORT=""

for URL in "${URLS[@]}"
do
    echo "Checking $URL"
    if ! is_up "$URL"; then
        REPORT+=" Down: $URL "
    fi
done

if [ -n "$REPORT" ]; then
    echo "$REPORT" | mail -r "$NOTIFY_FROM" -s "Sites down report" "$NOTIFY_TO"
fi