Monitor working status of two Pi-Hole

#!/bin/sh

# Monitors working status of two Pi-Hole devices
# Triggers a popup window on host if one or both aren't working
# Intended to run every 30 minutes via crontab
# Add something like this to crontab: 1,31 * * * * /home/stephen/.local/bin/pihole_check.sh

# Define the IP addresses or hostnames of the devices you want to ping
PIHOLE1="10.0.0.7"
PIHOLE2="10.0.0.8"
LOG_FILE="/home/stephen/ping_log.txt"
MAX_LOG_SIZE=12288  # 12KB
TRUNCATE_SIZE=10240  # 10KB

# Function to ping a device, check if it's reachable, and log the status
ping_and_log() {
    device_ip="$1"
    if ping -c 1 "$device_ip" > /dev/null 2>&1; then
        echo "$(date): $device_ip is reachable." >> "$LOG_FILE"
    else
        echo "$(date): $device_ip is not reachable." >> "$LOG_FILE"
        return 1
    fi
}

# Ping both Pi-Hole devices and log their status
if ! ping_and_log "$PIHOLE1" || ! ping_and_log "$PIHOLE2"; then
    # If any of the devices don't respond, display a warning window
    zenity --warning --text="At least one of the devices ($PIHOLE1 or $PIHOLE2) is not responding." --display=:0.0
fi

# Check and truncate the log file if its size exceeds 12KB
log_size=$(stat -c %s "$LOG_FILE" 2>/dev/null || echo 0)
if [ "$log_size" -gt "$MAX_LOG_SIZE" ]; then
    echo "Truncating log file..."
    tail -c "$TRUNCATE_SIZE" "$LOG_FILE" > "${LOG_FILE}.tmp" && mv "${LOG_FILE}.tmp" "$LOG_FILE"
fi