See blog post for more information: http://themodernscientist.com/posts/2013/2013-10-19-automated_notifications_of_experiment_progress_part_2/

Improved_Growl_Experiment_Status.sh

#!/bin/zsh

#### BEGIN USER CONFIG OPTIONS ####

# Path to the data file to watch for modifications
local_progress_file="/path/to/file_that_is_periodically_modified"

# Interval in minutes to wait between queries
# Must be an integer
interval_min=30

# User account and hostname of Mac where you will be notified
dest_user=your_login_name
dest_address=your_mac_hostname

# Set to 1 to enable data synchronization or 0 to disable
data_sync=1

# Paths for data synchronization
local_data_path="/path/to/local/data/directory"
remote_data_path="/path/to/remote/data/directory"

# Prowl API key
prowl_api_key="enter_your_api_key"

#### END USER CONFIG OPTIONS ####

# Calculate time to wait between checks in seconds
(( sleep_sec = $interval_min * 60 ))

# Check if the progress file exists
if [[ -f ${local_progress_file} ]]; then
    # Perform checks until the script is killed
    while ((1)); do

        # Check if the data file has been modified within the time period
        mod_file=`find ${local_progress_file} -mmin -${interval_min}`

        # Set notification message based on modification time of data file
        if [[ $mod_file == "" ]]; then
            message_string="NOTE: Experiment is stalled or complete."
        else
            message_string="OK: Experiment still running."
        fi
        
        # See if the remote computer is accessible
        ping -c 1 ${dest_address} >| /dev/null 2>&1
        ping_result=$? # Result will be 0 if computer is accessible

        if [[ $ping_result -eq 0 ]]; then

            # Synchronize the data if appropriate
            if (($data_sync)); then
                rsync --recursive --update --delete --owner --group \
                --perms --times --compress --rsh=ssh \
                ${local_data_path} ${dest_user}@${dest_address}:${remote_data_path}
            fi

            # Send the notification to your Mac
            ssh ${dest_user}@${dest_address} 'echo `/usr/local/bin/growlnotify \
            -p high -m "'$message_string'" -t "Experiment Update"`'

        else

            # Update notification if data could not be synchronized.
            if (($data_sync)); then
                message_string="$message_string Data not synchronized."
            fi

            # Send the notification directly to Prowl
            prowl_output=$(curl -s --data \
            "apikey=${prowl_api_key}&application=Experiment Update&event=${message_string}" \
            https://api.prowlapp.com/publicapi/add)
            
            # Parse the output to get the success/error code
            # Successive grep commands are used in lieu of other methods for BSD/GNU compatibility
            prowl_output_code=$(echo $prowl_output | grep -oE 'code="[0-9]+"' | grep -oE '[0-9]+')

            # Print a message if an error code was returned
            if [[ $prowl_output_code -ne 200 ]]; then
                echo "There was an error posting to Prowl: ${prowl_output_code}"
            fi
        fi

        # Wait until it's time to check again
        sleep $sleep_sec

    done
else
    # Data file not found
    echo "File ${local_progress_file} not found."
fi