check memory and restart service when less than X gb.

bash
#!/bin/bash

# Get the available memory in KB
free_mem_kb=$(free -k | grep Mem | awk '{print $4}')

# Convert to GB (divide by 1024^2)
# without bc
free_mem_gb=$((free_mem_kb / 1024 / 1024))
# with bc
# free_mem_gb=$(echo "scale=2; $free_mem_kb / (1024 * 1024)" | bc)

# Threshold for memory in GB
threshold=2

# Check if free memory is less than the threshold
# without bc
if [ "$free_mem_gb" -lt "$threshold" ]; then
# with bc
# if (( $(echo "$free_mem_gb < $threshold" | bc -l) )); then
    echo "Free memory is less than 2GB ($free_mem_gb GB). Restarting Apache..."
#    restart some service here
#    sudo systemctl restart apache2
else
    echo "Free memory is sufficient: $free_mem_gb GB."
fi