Uptime Monitor

gistfile1.sh

#!/bin/bash
#
# UPTIME MONITOR
# --------------
# Usage: Setup a cronjob to execute the script and your done.
#
# Copyright (c) 2012, T. Zengerink
# Licensed under MIT License.
# See: https://raw.github.com/gist/3151357/9e8e01df4ee12b1f04cd61e0ecee3ea8bd6f617b/mit-license.txt

# Setup variables
FROM_EMAIL="t.zengerink@gmail.com"
TO_EMAIL="t.zengerink@gmail.com"
CURL_TIMEOUT="5"

# Check if server is up
is_up()
{
  HOST="$1"
  [[ "$2" ]] && TO="$2" || TO="10"
  RESP=$(curl --connect-timeout $TO --write-out %{http_code} --silent --output /dev/null $HOST)
  [[ "$RESP" == "000" ]] && return 1 || return 0
}

# Send e-mail
send_email()
{
  (
  echo "To: $3"
  echo "Subject: Host $1 is down"
  echo ""
  echo "Host $1 is down."
  ) | sendmail -F "Uptime Monitor" -f "$2" -t
}

# Main
main()
{
  for SERVER in "$@"
  do  
    if ( ! is_up "$SERVER" "$CURL_TIMEOUT" )
    then
      send_email "$SERVER" "$FROM_EMAIL" "$TO_EMAIL"
    fi  
  done
}

# Execute main script
[[ "$@" ]] && main "$@" || echo "Usage: $0 [host1] [host2] [host3]"