A plugin written in perl to monitor and check thresholds for memory based on the output of the 'free -mt' command.

Ref: Nagios Exchange - check_mem page

Installation

1. Copy the file to your /usr/local/nagios/libexec directory of the host you are monitoring
2. Set the file mode to 755
3. Add a line to your nrpe.cfg file and restart the service.

command[check_mem]=/usr/local/nagios/libexec/check_mem -w 80,20 -c 95,50

4. Add the NRPE check to the appropriate configuration file on your Nagios server like:

define service{
        use                     servicetemplate2   
        hostgroup_name          linux-servers
        service_description     tmp
        check_command           check_nrpe!check_tmp
}

Command Line Syntax

# /usr/local/nagios/libexec/check_mem -w 50,20 -c 80,50
<b>WARNING: Memory Usage (W> 50, C> 80): 72% <br>Swap Usage (W> 20, C> 50): 0%</b> \
|MemUsed=72%;50;80 SwapUsed=0%;20;50

Display the Data

To add this to your "map" file for NagiosGraph, append the code to capture the data like below:

# Service type: check_mem
#   check command: check_nrpe!check_mem -w 50,10 -c 80,25
#   output: <b>CRITICAL: Memory Usage (W> 80, C> 95): 100% <br>Swap Usage (W> 20, C> 50): 0%</b>
#   perfdata: MemUsed=100%;80;95 SwapUsed=0%;20;50
/perfdata:.*MemUsed=(\d+)%;(\d+);(\d+).*?SwapUsed=(\d+)%;(\d+);(\d+)/
and push @s, [ memory,
       [ ramuse, GAUGE, $1 ],
       [ swapuse, GAUGE, $4 ] ];