Bash script to monitor memory usage on Linux
There are many open source monitoring tools are currently available in market to monitor Linux systems performance which will send an email alert when the system reaches the specified threshold limit.
It monitors everything such as CPU utilization, Memory utilization, swap utilization, disk space utilization and much more.
If you only have few systems and want to monitor them then writing a small shell script can make your task very easy.
In this tutorial we have added two shell script to monitor Memory utilization on Linux system.
When the system reaches the given threshold then it will trigger a mail to given email id.
Method-1 : Linux bash script to monitor memory utilization with email alert.
If you want to get only the current Memory utilization percentage through mail when the system reaches the given threshold, use the following script.
This is very simple and straightforward one line script. I preferred to go with this method for most of the time.
It will trigger an email when your system reaches 80% of Memory utilization.
*/5 * * * * /usr/bin/free | awk '/Mem/{printf("RAM Usage: %.2f%\n"), $3/$2*100}' | awk '{print $3}' | awk '{ if($1 > 80) print $0;}' | mail -s "High Memory Alert" [email protected]
Note: Please change the email id and Memory utilization threshold value as per your requirement
Output: You will be getting an email alert similar to below.
High Memory Alert: 80.40%
We have added many useful and interesting shell scripts in below link, feel free to check those
Method-2 : Linux bash script to monitor Memory Utilization with email alert.
If you want to get more information about the Memory utilization in the mail alert.
Then use the following script, which includes top Memory utilization process details based on the top Command and ps Command.
This will instantly gives you an idea what is going on your system and triggers an email when your system reaches 80% of Memory utilization.
Note: Please change the email id and Memory utilization threshold value as per your requirement.
# vi /opt/scripts/memory-alert.sh
#!/bin/sh
ramusage=$(free | awk '/Mem/{printf("RAM Usage: %.2f\n"), $3/$2*100}'| awk '{print $3}')
if [ "$ramusage" > 20 ]; then
SUBJECT="ATTENTION: Memory Utilization is High on $(hostname) at $(date)"
MESSAGE="/tmp/Mail.out"
TO="[email protected]"
echo "Memory Current Usage is: $ramusage%" >> $MESSAGE
echo "" >> $MESSAGE
echo "------------------------------------------------------------------" >> $MESSAGE
echo "Top Memory Consuming Process Using top command" >> $MESSAGE
echo "------------------------------------------------------------------" >> $MESSAGE
echo "$(top -b -o +%MEM | head -n 20)" >> $MESSAGE
echo "" >> $MESSAGE
echo "------------------------------------------------------------------" >> $MESSAGE
echo "Top Memory Consuming Process Using ps command" >> $MESSAGE
echo "------------------------------------------------------------------" >> $MESSAGE
echo "$(ps -eo pid,ppid,%mem,%cpu,cmd --sort=-%mem | head)" >> $MESSAGE
mail -s "$SUBJECT" "$TO" < $MESSAGE
rm /tmp/Mail.out
fi
Finally add a cronjob to automate this. It will run every 5 minutes.
# crontab -e */5 * * * * /bin/bash /opt/scripts/memory-alert.sh
Note: Since the script has scheduled to run once for every 5 minutes , you will be getting the email alert on 5 minutes interval
Say for example If your system reaches the given limit after 8.25 minutes then you will be getting an email alert on the second cycle i.e after 10 minutes ( 2nd 5 minute cycle)
Output: You will be getting an email alert similar to below alert.
Memory Current Usage is: 80.71% +------------------------------------------------------------------+ Top Memory Consuming Process Using top command +------------------------------------------------------------------+ top - 12:00:58 up 5 days, 9:03, 1 user, load average: 1.82, 2.60, 2.83 Tasks: 314 total, 1 running, 313 sleeping, 0 stopped, 0 zombie %Cpu0 : 8.3 us, 12.5 sy, 0.0 ni, 75.0 id, 0.0 wa, 0.0 hi, 4.2 si, 0.0 st %Cpu1 : 13.6 us, 4.5 sy, 0.0 ni, 81.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu2 : 21.7 us, 21.7 sy, 0.0 ni, 56.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu3 : 13.6 us, 9.1 sy, 0.0 ni, 77.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu4 : 17.4 us, 8.7 sy, 0.0 ni, 73.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu5 : 20.8 us, 4.2 sy, 0.0 ni, 70.8 id, 0.0 wa, 0.0 hi, 4.2 si, 0.0 st %Cpu6 : 9.1 us, 0.0 sy, 0.0 ni, 90.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu7 : 17.4 us, 4.3 sy, 0.0 ni, 78.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 16248588 total, 5015964 free, 6453404 used, 4779220 buff/cache KiB Swap: 17873388 total, 16928620 free, 944768 used. 6423008 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 17163 daygeek 20 2033204 487736 282888 S 10.0 3.0 8:26.07 /usr/lib/firefox/firefox -contentproc -childID 15 -isForBrowser -prefsLen 9408 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /u+ 1121 daygeek 20 4191388 419180 100552 S 5.0 2.6 126:02.84 /usr/bin/gnome-shell 1902 daygeek 20 1701644 327216 82536 S 20.0 2.0 153:27.92 /opt/google/chrome/chrome 2969 daygeek 20 1051116 324656 92388 S 15.0 2.0 149:38.09 /opt/google/chrome/chrome --type=renderer --field-trial-handle=10346122902703263820,11905758137655502112,131072 --service-pipe-token=1339861+ 1068 daygeek 20 1104856 309552 278072 S 5.0 1.9 143:47.42 /usr/lib/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty -verbose 3 27246 daygeek 20 907344 265600 108276 S 30.0 1.6 10:42.80 /opt/google/chrome/chrome --type=renderer --field-trial-handle=10346122902703263820,11905758137655502112,131072 --service-pipe-token=8587368+ +------------------------------------------------------------------+ Top Memory Consuming Process Using ps command +------------------------------------------------------------------+ PID PPID %MEM %CPU CMD 8223 1 6.4 6.8 /usr/lib/firefox/firefox --new-window 13948 1121 6.3 1.2 /usr/bin/../lib/notepadqq/notepadqq-bin 8671 8223 4.4 7.5 /usr/lib/firefox/firefox -contentproc -childID 5 -isForBrowser -prefsLen 6999 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab 17163 8223 3.0 0.6 /usr/lib/firefox/firefox -contentproc -childID 15 -isForBrowser -prefsLen 9408 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab 1121 1078 2.5 1.6 /usr/bin/gnome-shell 17937 8223 2.5 0.8 /usr/lib/firefox/firefox -contentproc -childID 16 -isForBrowser -prefsLen 9410 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab 8499 8223 2.2 0.6 /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -prefsLen 6635 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab 8306 8223 2.2 0.8 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -prefsLen 1 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab 9198 8223 2.1 0.6 /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -prefsLen 8604 -prefMapSize 184979 -parentBuildID 20190521202118 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 8223 true tab
