Tag Archives: Nagios

Nagios Plugin – check_mem

check_mem is a simple Nagios plugin to check memory utilisation on Linux servers. I have written both a bash and a Ruby version of this script.

bash version:

Ruby version:


Installing Nagios under Nginx on Ubuntu 14.04 LTS

Nagios is an excellent open source monitoring solution that can be configured to monitor pretty much anything. In this article, I’ll describe how to install Nagios under Nginx on Ubuntu 14.04 LTS.

First of all, check that the system is fully up to date:

Next, install the build-essential package so that we can build Nagios and its plugins from source:

Install Nginx, and verify that it has started:

Install libgd2-xpm-dev, php5-fpm, spawn-fcgi and fcgiwrap:

Next, create a nagios user:

Issue the following commands to create a nagcmd group, and add it as a secondary group to both the nagios and www-data users:

Download the latest Nagios core distribution from http://www.nagios.org/download – at the time of writing this was version 4.0.7.

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GNU and UNIX Commands: Using a while Loop to Populate Configuration File

I recently had a need to generate a lot of Nagios host definitions. The hosts all had a similar naming convention:


Here, nnnn was a zero-padded number from 0 to 9999. In this particular environment, there were 41 hosts. A simple multiline echo command inside a while loop fed by seq produces the appropriate host stanzas we can add to our Nagios configuration. We also look up the servers IP addresses via the host command and insert those too:

The -w option to seq causes it to output a leading-zero padded number. Redirect the output of this loop to a file, and you’ll have your Nagios host configuration. This is another reasons why having a naming convention for a large number of servers is important – it will aid you in automation and administration down the track.