memory_monitor.bash

memory_monitor.bash

#!/usr/bin/env bash

# memory monitor script
# Henri Shustak
# (C) 2022 GNU GPL v3 or later

# basic path setup (good for most systems)
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# settings (this could be improved to use percentages)...
memory_check_interval=520 # seconds
memory_low_threshold=1500 # megabytes
swap_low_threshold=9000   # megabyes
email_sender="[email protected]"
email_alerts="[email protected]"
memory_log_file="/tmp/memory_free.log"
# create the log file
touch $memory_log_file
chmod 755 $memory_log_file

while true ; do
    # check free memory
    current_free_memory=$(free -m | grep "^Mem" | sed 's/\s\+/ /g' | cut -d " " -f 7)
    if [[ $current_free_memory -le $memory_low_threshold ]] ; then
        echo "WARNING! Low Swap Detected : Available Memory : $current_free_memory MB" | mailx -aFrom:"Memory Monitor <$email_sender>" -s "$(hostname) : Low Memory" $email_alerts
    fi
    # check free swap
    current_free_swap=$(free -m | grep "^Swap" | sed 's/\s\+/ /g' | cut -d " " -f 4)
    if [[ $current_free_swap -le $swap_low_threshold ]] ; then
        echo "WARNING! Low Swap Detected : Available Swap : $current_free_swap MB" | mailx -aFrom:"Memory Monitor <$email_sender>" -r $email_sender -s "$(hostname) : Low Swap" $email_alerts
    fi
    # log free memory to /tmp/free_memory.log
    echo "$(date)     |    current_free_memory : ${current_free_memory} MB    |    current_free_swap : ${current_free_swap} MB     " >> ${memory_log_file}
    # hang tight for next check
    sleep $memory_check_interval
done

memory_monitor.service

[Unit]
Description=Memory Monitoring Script
After=network.target

[Service]
Type=simple
ExecStart=/path/to/memory_monitor.bash

[Install]
WantedBy=multi-user.target