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9 votes
Current Version
Last Release Date
Compatible With
  • Nagios 2.x
  • Nagios 3.x
check_memNagios plugin
check_mem.phppnp template
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check_mem is a bash script that checks buffer, cache and used memory with performance data enable
root@localhost # ./check_mem
[MEMORY] Total: 7713 MB - Used: 2402 MB - 31% [SWAP] Total: 8189 MB - Used: 0 MB - 0% | MTOTAL=8087736320;;;; MUSED=2516549632;;;; MCACHE=2323607552;;;; MBUFFER=140218368;;;; STOTAL=8587833344;;;; SUSED=0;;;;

To use it with nrpe:

add command:

# check_nrpe_memory
define command {
command_name check_nrpe_memory
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c memory

define service:

# Memory
define service {
use default-service
host_name some_host
service_description Memory Usage
check_command check_nrpe_memory

and define nrpe command:

command[memory]=/opt/plugins/check_mem -w 80 -c 90
Reviews (8)
Because I'm fairly inexperienced at managing Nagios, I had to hunt around to figure everything out.

Hopefully this will be helpful to others:

I added the command to objects/commands.cfg
I added the service to servers/services.cfg
I added the command to etc/nrpe.cfg on both the Nagios Server and the target Host

I added a line to nrpe/common.cfg on both servers of:
command[memory]=/usr/local/nagios/libexec/check_mem $ARG1$ $ARG2$

I restarted nrpe (xinetd) on the target host(s) with:
sudo systemctl restart xinetd

I restarted nagios on the nagios server
sudo systemctl restart nagios
byFonant, September 2, 2015
Nice script, however I've noticed that my server with 16G of RAM results in the "total" value in bytes from the "free" command being truncated: a bug in "free" rather this script. This results in erroneous values from this script, and the "USED" value can go negative.

I've updated my copy so it uses kilobytes instead of bytes for the fine-resolution numbers.
bydot, November 17, 2014
2 of 2 people found this review helpful
Why do you call 'free' eight times? Why not 100?
substitute this stuff
memTotal_b=`free -b |grep Mem |awk '{print $2}'`
memFree_b=`free -b |grep Mem |awk '{print $4}'`
memBuffer_b=`free -b |grep Mem |awk '{print $6}'`
memCache_b=`free -b |grep Mem |awk '{print $7}'`

memTotal_m=`free -m |grep Mem |awk '{print $2}'`
memFree_m=`free -m |grep Mem |awk '{print $4}'`
memBuffer_m=`free -m |grep Mem |awk '{print $6}'`
memCache_m=`free -m |grep Mem |awk '{print $7}'`


mem=`free -m |grep Mem`
"free -m |grep Mem"
with echo $mem
byniemi, November 5, 2014
Nagios 3.0.6
making some changes, remove some spaces and ";" and it works on my nagios. Thanks to Athor!

if [ "$1" = "-w" ] && [ "$2" -gt "0" ] && [ "$3" = "-c" ] && [ "$4" -gt "0" ]; then

memTotal_b=`free -b |grep Mem |awk '{print $2}'`
memFree_b=`free -b |grep Mem |awk '{print $4}'`
memBuffer_b=`free -b |grep Mem |awk '{print $6}'`
memCache_b=`free -b |grep Mem |awk '{print $7}'`

memTotal_m=`free -m |grep Mem |awk '{print $2}'`
memFree_m=`free -m |grep Mem |awk '{print $4}'`
memBuffer_m=`free -m |grep Mem |awk '{print $6}'`
memCache_m=`free -m |grep Mem |awk '{print $7}'`



if [ "$memUsedPrc" -ge "$4" ]; then
echo "Memory: CRITICAL Total: $memTotal_m MB - Used: $memUsed_m MB - $memUsedPrc% used!|Total=$memTotal_b;;;Used=$memUsed_b;;;Cache=$memCache_b;;;Buffer=$memBuffer_b;;;"
$(exit 2)
elif [ "$memUsedPrc" -ge "$2" ]; then
echo "Memory: WARNING Total: $memTotal_m MB - Used: $memUsed_m MB - $memUsedPrc% used!|Total=$memTotal_b;;;Used=$memUsed_b;;;Cache=$memCache_b;;;Buffer=$memBuffer_b;;;"
$(exit 1)
echo "Memory: OK Total: $memTotal_m MB - Used: $memUsed_m MB - $memUsedPrc% used|Total=$memTotal_b;;;Used=$memUsed_b;;;Cache=$memCache_b;;Buffer=$memBuffer_b;;;"
$(exit 0)

echo "check_mem v1.1"
echo ""
echo "Usage:"
echo " -w -c "
echo ""
echo "warnlevel and critlevel is percentage value without %"
echo ""
echo "Copyright (C) 2012 Lukasz Gogolin ("
bywhereisaaron, April 12, 2014
1 of 1 people found this review helpful
I tested this plug-in and liked it a lot. There are others but this one doesn't have any dependencies other than 'bash' and 'free', and makes a nice chart.

I felt it was a little inefficient so I made some tweaks to reduce the number of forks required. I also tweaked the chart. My changes are on Github.
byHFroyen, October 17, 2013
I also cat the and touch new file and paste it in. In the nrpe_local.cfg I put /path/to/plugins/ -w value -c value
I put the PHP file in the pnp-templates path, made command and service definition.

Is it also possible to do this for Windows Servers via NSClient++ or NSCP?

Great job on this!
Love the plugin and its very useful. Only in my setup it produces separate graphs for every type of memory metric. On your sample image you have a consolidated graphs where different metrics are shown in different colors. How did you do it? Thanks in advance!
bydick, January 25, 2013
2 of 2 people found this review helpful
This plugin works nicely with very good looking pnp charting support. Only problems I had were not related to the code itself.

The script download comes in a weird encoding that does not work in Linux. UTF-8 Unicode (with BOM) text, with CRLF line terminators

I didn't feel like looking around to convert this so I just cat the file and pasted into a new file, which worked fine.

Also note that the pnp template file, check_nrpe_memory.php, should be moved to /etc/pnp4nagios/templates or where your pnp configs are set to. Also unless you name the check nrpe_memory, you're going to have to rename the file to check_.php

Thanks for the great plugin and pnp template.